birth order theory essay

The Reporter

New Evidence on the Impacts of Birth Order

What determines a child's success? We know that family matters — children from higher socioeconomic status families do better in school, get more education, and earn more.

However, even beyond that, there is substantial variation in success across children within families. This has led researchers to study factors that relate to within-family differences in children's outcomes. One that has attracted much interest is the role played by birth order, which varies systematically within families and is exogenously determined.

While economists have been interested in understanding human capital development for many decades, compelling economic research on birth order is more recent and has largely resulted from improved availability of data. Early work on birth order was hindered by the stringent data requirements necessary to convincingly identify the effects of birth order. Most importantly, one needs information on both family size and birth order. As there is only a third-born child in a family with at least three children, comparing third-borns to firstborns across families of different sizes will conflate the birth order effect with a family size effect, so one needs to be able to control for family size. Additionally, it is beneficial to have information on multiple children from the same family so that birth order effects can be estimated from within-family differences in child outcomes; otherwise, birth order effects will be conflated with other effects that vary systematically with birth order, such as cohort effects. Large Scandinavian register datasets that became available to researchers beginning in the late 1990s have enabled birth order research, as they contain population data on both family structure and a variety of child outcomes. Here, I describe my research with a number of coauthors, using these data to explore the effects of birth order on outcomes including human capital accumulation, earnings, development of cognitive and non-cognitive skills, and health.

Birth Order and Economic Success

Almost a half-century ago, economists including Gary Becker, H. Gregg Lewis, and Nigel Tomes created models of quality-quantity trade-offs in child-rearing and used these models to explore the role of family in children's success. They sought to explain an observed negative correlation between family income and family size: if child quality is a normal good, as income rises the family demands higher-quality children at the cost of lower family size. 1

However, this was a difficult model to test, as characteristics other than family income and child quality vary with family size. The introduction of natural experiments, combined with newly available large administrative datasets from Scandinavia, made testing such a model possible.

In my earliest work on the topic, Paul Devereux, Kjell Salvanes, and I took advantage of the Norwegian administrative dataset and set out to better understand this theoretical quantity-quality tradeoff. 2 It became clear that child "quality" was not a constant within a family — children within families were quite different, despite the model assumptions to the contrary. Indeed, we found that birth order could explain a large fraction of the family size differential in children's educational outcomes. Average educational attainment was lower in larger families largely because later-born children had lower average education, rather than because firstborns had lower education in large families than in small families. We found that firstborns had higher educational attainment than second-borns who in turn did better than third-borns, and so on. These results were robust to a variety of specifications; most importantly, we could compare outcomes of children within the same families.

To give a sense of the magnitude of these effects: The difference in educational attainment between the first child and the fifth child in a five-child family is roughly equal to the difference between the educational attainment of blacks and whites calculated from the 2000 Census. We augmented the education results by examining earnings, whether full-time employed, and whether one had a child as a teenager as additional outcome variables, and found strong evidence for birth order effects, particularly for women. Later-born women have lower earnings (whether employed full-time or not), are less likely to work full-time, and are more likely to have their first child as teenagers. In contrast, while later-born men have lower full-time earnings, they are not less likely to work full-time [Figure 1].

Birth Order and Cognitive Skills

One possible explanation for these differences is that cognitive ability varies systematically by birth order. In subsequent work, Devereux, Salvanes, and I examined the effect of birth order on IQ scores. 3

The psychology literature has long debated the role of birth order in determining children's IQs; this debate was seemingly resolved when, in 2000, J. L. Rodgers et al. published a paper in American Psychologist entitled "Resolving the Debate Over Birth Order, Family Size, and Intelligence" that referred to the apparent relationship between birth order and IQ as a "methodological illusion." 4 However, this work was limited due to the absence of large representative datasets necessary to identify these effects. We again used population register data from Norway to estimate this relationship.

To measure IQ, we used the outcomes of standardized cognitive tests administered to Norwegian men between the age of 18 and 20 when they enlist in the military. Consistent with our earlier findings on educational attainment but in contrast to the previous work in the literature, we found strong birth order effects on IQ that are present when we look within families. Later-born children have lower IQs, on average, and these differences are quite large. For example, the difference between firstborn and second-born average IQ is on the order of one-fifth of a standard deviation, or about three IQ points. This translates into approximately a 2 percent difference in annual earnings in adulthood.

The Effect of Birth Order on Non-Cognitive Skills

Personality is another factor that is posited to vary by birth order, a proposition that has been particularly difficult to assess in a compelling way due to the paucity of large datasets containing information on individual personality. In recent work on the topic, Erik Gronqvist, Bjorn Ockert, and I use Swedish administrative datasets to examine this issue. 5

In the economics literature, personality traits are often referred to as non-cognitive abilities and denote traits that can be distinguished from intelligence. 6 To measure "personality" (or non-cognitive skills), we use the outcome of a standardized psychological evaluation, conducted by a certified psychologist, that is performed on all Swedish men between the ages of 18 and 20 when they enlist in the military, and which is strongly related to success in the labor market. An individual is given a higher score if he is considered to be emotionally stable, persistent, socially outgoing, willing to assume responsibility, and able to take initiative. Similar to the results for cognitive skills, we find evidence of consistently lower scores in this measure for later-born children. Third-born children have non-cognitive abilities that are 0.2 standard deviations below firstborn children. Interestingly, boys with older brothers suffer almost twice as much in terms of these personality characteristics as boys with older sisters.

Importantly, we also demonstrate that these personality differences translate into differences in occupation choice by birth order. Firstborn children are significantly more likely to be employed and to work as top managers, while later-born children are more likely to be self-employed. More generally, firstborn children are more likely to be in occupations requiring sociability, leadership ability, conscientiousness, agreeableness, emotional stability, extraversion, and openness.

The Effect of Birth Order on Health

Finally, how do these differences translate into later health? In more recent work, Devereux, Salvanes, and I analyze the effect of birth order on health. 7 There is a sizable body of literature about the relationship between birth order and adult health; individual studies have typically examined only one or a small number of health outcomes and, in many cases, have used relatively small samples. Again, we use large nationally representative data from Norway to identify the relationship between birth order and health when individuals are in their 40s, where health is measured along a number of dimensions, including medical indicators, health behaviors, and overall life satisfaction.

The effects of birth order on health are less straightforward than other outcomes we have examined, as firstborns do better on some dimensions and worse on others. We find that the probability of having high blood pressure declines with birth order, and the largest gap is between first- and second-borns. Second-borns are about 3 percent less likely to have high blood pressure than firstborns; fifth-borns are about 7 percent less likely to have high blood pressure than firstborns. Given that 24 percent of this population has high blood pressure, this is quite a large difference. Firstborns are also more likely to be overweight and obese. Compared with second-borns, firstborns are 4 percent more likely to be overweight and 2 percent more likely to be obese. The equivalent differences between fifth-borns and firstborns are 10 percent and 5 percent. For context, 47 percent of the population is overweight and 10 percent is obese. Once again, the magnitudes are quite large.

However, later-borns are less likely to consider themselves to be in good health, and measures of mental health generally decline with birth order. Later-born children also exhibit worse health behaviors. The number of cigarettes smoked daily increases monotonically with birth order, suggesting that the higher prevalence of smoking by later-borns found among U.S. adolescents by Laura M. Argys et al. 8 may persist throughout adulthood and, hence, have important effects on health outcomes.

Possible Mechanisms

Why are adult outcomes likely to be affected by birth order? A host of potential explanations has been proposed across several academic disciplines.

A number of biological factors may explain birth order effects. These relate to changes in the womb environment or maternal immune system that occur over successive births. Beyond biology, parents could have other influences. Childhood inputs, especially in the first years of life, are considered crucial for skill formation. 9 Firstborn children have the full attention of parents, but as families grow the family environment is diluted and parental resources become scarcer. 10 In contrast, parents are more experienced and tend to have higher incomes when raising later-born children. In addition, for a given amount of resources, parents may treat firstborn children differently than second- or later-born children. Parents may use more strict parenting practices toward the firstborn, so as to gain a reputation for "toughness" necessary to induce good behavior among later-borns. 11

There are also theories that suggest that interactions among siblings can shape birth order effects. For example, based on evolutionary psychology, Frank J. Sulloway suggests that firstborns have an advantage in following the status quo, while later-borns — by having incentives to engage in investments aimed at differentiating themselves — become more sociable and unconventional in order to attract parental resources. 12

In each of these papers, we attempted to identify potential mechanisms for the patterns we observed. However, it is here we see the limitations of these large administrative datasets, as for the most part, we lack necessary detailed information on biological factors and on household dynamics when the children are young. However, we do have some evidence on the role of biological factors. Later-born children tend to have better birth outcomes as measured by factors such as birth weight. In our Swedish data, we took advantage of the fact that some children's biological birth order is different from their environmental birth order, due to the death of an older sibling or because their parent gave up a child for adoption. When we examine this subsample, we find that the birth order effect on occupational choice is entirely driven by the environmental birth order, again suggesting that biological factors may not be central.

Also in our Swedish study, we found that firstborn teenagers are more likely to read books, spend more time on homework, and spend less time watching TV or playing video games. Parents spend less time discussing school work with later-born children, suggesting there may be differences in parental time investments. Using Norwegian data, we found that smoking early in pregnancy is more prevalent for first pregnancies than for later ones. However, women are more likely to quit smoking during their first pregnancy than during later ones, and firstborns are more likely to be breastfed. These findings suggest that early investments may systematically benefit firstborns and help explain their generally better outcomes.

In the past two decades, with the increased accessibility of administrative datasets on large swaths of the population, economists and other researchers have been better able to identify the role of birth order in the outcomes of children. There is strong evidence of substantial differences by birth order across a range of outcomes. While I have described several of my own papers on the topic, a number of other researchers have also taken advantage of newly available datasets in Florida and Denmark to examine the role of birth order on other important outcomes, specifically juvenile delinquency and later criminal behavior. 13 Consistent with the work discussed here, later-born children experience higher rates of delinquency and criminal behavior; this is at least partly attributable to time investments of parents.

Researchers

More from nber.

G. Becker, "An Economic Analysis of Fertility," in Demographic and Economic Change in Developed Countries , New York, Columbia University Press, 1960, pp. 209-40; G. Becker and H. Lewis, "Interaction Between Quantity and Quality of Children," in Economics of the Family: Marriage, Children, and Human Capital , 1974, pp. 81-90; G. Becker and N. Tomes, "Child Endowments, and the Quantity and Quality of Children," NBER Working Paper 123 , February 1976.  

S. Black, P. Devereux, and K. Salvanes, "The More the Merrier? The Effect of Family Composition on Children's Education" NBER Working Paper 10720 , September 2004, and Quarterly Journal of Economics , 120(2), 2005, pp. 669-700.  

S. Black, P. Devereux, and K. Salvanes, "Older and Wiser? Birth Order and the IQ of Young Men," NBER Working Paper 13237 , July 2007, and CESifo Economic Studies , Oxford University Press, vol. 57(1), pages 103-20, March 2011.  

J. Rodgers, H. Cleveland, E. van den Oord, and D. Rowe, "Resolving the Debate Over Birth Order, Family Size, and Intelligence," American Psychologist , 55(6), 2000, pp. 599-612.

S. Black, E. Gronqvist, and B. Ockert, "Born to Lead? The Effect of Birth Order on Non-Cognitive Abilities," NBER Working Paper 23393 , May 2017.  

L. Borghans, A. Duckworth, J. Heckman, and B. ter Weel, "The Economics and Psychology of Personality Traits," Journal of Human Resources , 43, 2008, pp. 972-1059.  

S. Black, P. Devereux, K. Salvanes, "Healthy (?), Wealthy, and Wise: Birth Order and Adult Health, NBER Working Paper 21337 , July 2015.  

L. Argys, D. Rees, S. Averett, and B. Witoonchart, "Birth Order and Risky Adolescent Behavior," Economic Inquiry , 44(2), 2006, pp. 215-33.  

F. Cunha and J. Heckman, "The Technology of Skill Formation," NBER Working Paper 12840 , January 2007.

R. Zajonc and G. Markus, "Birth Order and Intellectual Development," Psychological Review , 82(1), 1975, pp. 74-88; R. Zajonc, "Family Configuration and Intelligence," Science , 192(4236), 1976, pp. 227-36; J. Price, "Parent-Child Quality Time: Does Birth Order Matter?" in Journal of Human Resources , 43(1), 2008, pp. 240-65; J.Lehmann, A. Nuevo-Chiquero, and M. Vidal-Fernandez, "The Early Origins of Birth Order Differences in Children's Outcomes and Parental Behavior," forthcoming in Journal of Human Resources .  

V. Hotz and J. Pantano, "Strategic Parenting, Birth Order, and School Performance," NBER Working Paper 19542 , October 2013, and Journal of Population Economics , 28(4), 2015, pp. 911-936. ↩  

F. Sulloway, Born to Rebel: Birth Order, Family Dynamics, and Creative Lives , New York, Pantheon Books, 1996.

S. Breining, J. Doyle, D. Figlio, K. Karbownik, J. Roth, "Birth Order and Delinquency: Evidence from Denmark and Florida," NBER Working Paper 23038 , January 2017.

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Alfred Adler Birth Order Theory Explained

Alfred Adler believed that the birth order of a group of siblings would help to determine individual personalities. Although family situations are unique and individualize, Adler believed that generic principles to family situations could dramatically impact how a child develops over time.

The structure of the family also matters in Adler’s theory. Families with all boys or all girls may see changes to the personality structures that he developed, for example, compared to families that had an even mix of boys and girls or had an only child.

An Overview of the Alfred Adler Birth Order Theory

In Adler’s birth order theory, there are three key observations which must be made. One must look at the position of the child in the family, what the family situation happens to be, and what characteristics develop because of that combination.

Here are some of the general expectations to expect from a child’s personality when using Adler’s birth order theory to evaluate children.

Only Child: An only child tends to receive the full attention of both parents. They can be over-protected, but they can also be spoiled. This causes the child to like being the center of attention, prefer adult company, and have difficulty sharing with others.

Oldest Child: The eldest child in a family goes from being an only child to the oldest child. That requires the child to learn how to share. Expectations are usually very high, which includes the need for the child to set an example for other siblings. This causes the child to trend toward authoritarian and strict approaches. They feel powerful and often require encouragement to be helpful.

Youngest Child: The youngest child in a family often sees every sibling as a potential “mother” and “father.” Just about everyone tells them what to do and when to do it. Their role is never removed. This causes the child to want to grow up more quickly and make big plans that may never come true.

Middle Child: Because the oldest receives responsibility and the youngest can be spoiled, children in the middle can feel like they don’t receive any attention at all. They fight for significance and privilege. This causes the child to develop an attitude that is very black-and-white. They tend to be even-tempered and fight to protect the social justice of others, but can also feel very lonely.

Twins: One twin is usually stronger than the other twin. One may be more active. Some families may see the older twin as being the oldest child. Because they are born together, there isn’t the same transition issues from an only child, but there can also be some identity problems. One twin tends to become the “leader” and the other is the “follower.”

Ghost Child: Some children are born into families where a first child may have died before they were born. This causes parents, especially mothers, to become over-protective of all their children, but especially their oldest. Children in this position often become rebellious or may attempt to exploit their parent’s feelings for personal gain.

Adopted Child: Many adopted children receive the same levels of attention that an only child receives. Parents who adopt tend to try to compensate the child for the loss of their biological parents. This causes the child to become demanding, lack in self-confidence, and even resent their family over time.

What About Single Girls or Single Boys in a Sibling Group?

The most unique aspects of the Adler birth order theory involve families where there is a sibling group, but only one boy or one girl in that group. When there is only one boy with a group of sisters, they tend to prefer spending time with women over men. Boys in this position can be very distant from their fathers. Many try to “prove” they are a man in the family.

For girls, the brothers tend to act as a protector. This can lead girls in this position to become extremely feminine, taking on the “princess personality,” or become a tomboy and attempt to “conquer” her brothers. Fathers tend to play a dominant role in the personality development of girls in this position.

In families that are all boys or all girls, the assigned roles can blur. If the parents wanted a child of the other gender, then that role may be assigned to one of the children. This can cause the child to rebel, to accept their role, or have resentment fester over time. Adler believed that the differences he saw in birth order could fade, in time, if families became less competitive. In a democratic, cooperative environment, he felt like all these differences could disappear.

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How Does Birth Order Shape Your Personality?

Beware the stereotypes

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What Is Adler’s Birth Order Theory?

First-born child, middle child.

• Impact on Relationships

Debunking Myths and Limitations

Birth order refers to the order a child is born in relation to their siblings, such as whether they are first-born, middle-born, or last-born. You’ve probably heard people joke about how the eldest child is the bossy one, the middle child is the peace-maker, and the youngest child is the irresponsible rebel—but is there any truth to these stereotypes?

Psychologists often look at how birth order can affect development, behavior patterns, and personality characteristics, and there is some evidence that birth order might play a role in certain aspects of personality .

At a Glance

Researchers often explore how birth order, including the differences in parental expectations and sibling dynamics, can affect development and character. According to some researchers, firstborns, middle children, youngest-children, and only child-children often exhibit distinctive characteristics that are strongly influenced by how birth order shapes parental and sibling behaviors.

Early in the 20th century, the Austrian psychiatrist Alfred Adler introduced the idea that birth order could impact development and personality. Adler, the founder of individual psychology, was heavily influenced by psychoanalyst Sigmund Freud .

Key points of Adler's birth order theory were that firstborns were more likely to develop a strong sense of responsibility, middleborns a desire for attention, and lastborns a sense of adventure and rebellion.

Adler also notably introduced the concept of the " family constellation ." This idea emphasizes the dynamics that form between family members and how these interactions play a part in shaping individual development.

Adler's birth order theory suggests that firstborns get more attention and time from their parents. New parents are still learning about child-rearing, which means that they may be more rule-oriented, strict, cautious, and sometimes even neurotic .

They are often described as responsible leaders with Type A personalities , a phenomenon sometimes referred to as " oldest-child syndrome ."

"Older siblings, regardless of gender, often feel more deprived or envious since they have experienced having another child divert attention away from them at some point in their lives. They tend to be more success-oriented,” explains San Francisco therapist Dr. Avigail Lev.

Firstborn children are often described as:

• High-achieving (or sometimes even over-achieving )
• Structured and organized
• Responsible

All this extra attention firstborns enjoy changes abruptly when younger siblings come along. When you become an older sibling, you suddenly have to share your parent's attention. You may feel that your parents have higher expectations for you and look to you to set an example for your younger siblings.

Consider the experiences of the oldest siblings, who are frequently tasked with caring for younger siblings. Because they are often expected to help fill the role of caregivers, they may be more nurturing, responsible, and motivated to excel.

Such traits are affected not only by birth order but also by how your position in the family affects your parent's expectations and your relationship with your younger siblings.

Research has found that firstborn kids tend to have more advanced cognitive development , which may also confer advantages when it comes to school readiness skills. However, it's important to remember that being the oldest child can also come with challenges, including carrying the weight of expectations and the burden of taking a caregiver role within the family.

Adler suggested that middle children tend to become the family’s peacemaker since they often have to mediate conflicts between older and younger siblings. Because they tend to be overshadowed by their eldest siblings, middle children may seek social attention outside of the family.

In families with three children, the youngest male sibling is likely to be more passive or easy-going.

Middleborns are often described as:

• Independent
• Peacemakers
• People pleasers
• Attention-seeking
• Competitive

While they tend to be adaptable and independent, they can also have a rebellious streak that tends to emerge when they want to stand apart from their siblings.

" Middle child syndrome " is a term often used to describe the negative effects of being a middle child. Because middle kids are sometimes overlooked, they may engage in people-pleasing behaviors as adults as a way to garner attention and favor in their lives.

While research is limited, some studies have shown that middle kids are less likely to feel close to their mothers and are more likely to have problems with delinquency.

Some research suggests that middle children may be more sensitive to rejection . As a middle child, you may feel like you didn't get as much attention and were constantly in competition with your siblings. You may struggle with feelings of insecurity, fear of rejection, and poor self-confidence .

Lastborns, often referred to as the "babies" of the family, are often seen as spoiled and pampered compared to their older siblings. Because parents are more experienced at this point (and much busier), they often take a more laissez-faire approach to parenting . 

Last-born children are sometimes described as:

• Free-spirited
• Manipulative
• Self-centered
• Risk-taking

Adler's theory suggests that the youngest children tend to be outgoing, sociable, and charming. While they often have more freedom to explore, they also often feel overshadowed by their elder siblings, referred to as " youngest child syndrome ."

Because parents are sometimes less strict and disciplined with last-borns, these kids may have fewer self-regulation skills.

"If the youngest of many children is female, she tends to be more coddled or cared for, leading to a greater reliance on others compared to her older siblings, especially in larger families," Lev suggests.

Only children are unique in that they never have to share their parents' attention and resources with a sibling. It can be very much like being a firstborn in many ways. These kids may be doted on by their caregivers, but never have younger siblings to interact with, which may have an impact on development.

Only children are often described as:

• Perfectionistic
• High-achieving
• Imaginative
• Self-reliant

Because they interact with adults so much, only children often seem very mature for their age. If you're an only child, you may feel more comfortable being alone and enjoy spending time in solitude pursuing you own creative ideas. You may like having control and, because of your parents' high expectations, have strong perfectionist tendencies .

How Birth Order Influences Relationships

Birth order may affect relationships in a wide variety of ways. For example, it may impact how you form connections with other people. It can also affect how you behave within these relationships.

Dr. Lev suggests that the effects of birth order can differ depending on gender. 

"For instance, in a family with two female siblings, the younger one often appears more confident and empowered, while the older one is more achievement-focused and insecure," she explains.

She also suggests that there is often a notable rivalry between same-sex siblings versus that of mixed-gender siblings. Again, this effect can vary depending on gender. Where an older sister might be less secure and the younger sister more secure, the opposite is often true when it comes to older and younger brothers.

"This could be because older sisters often assume a motherly role, while older brothers might take on more of a bully role. As a result, younger brothers are generally more insecure, whereas younger sisters tend to be more confident than their older siblings," she explains.

Some other potential effects include:

Communication

Birth order can affect how you communicate with others, which can have a powerful impact on relationship dynamics.

• Firstborns and only children are often seen as more direct, which others can sometimes interpret as bossy or controlling.
• Middle children may be less confrontational and more likely to look for solutions that will accommodate everyone.
• Lastborns, on the other hand, may rely more on their sense of humor and charm to guide their social interactions.

Relationship Roles

Birth order may also influence the roles that you take on in a relationship.

• Firstborns, for example, may be more likely to take on a caregiver role. This can be nurturing and supportive, but it can sometimes make partners feel like they are being "parented." 
• Middle children are more likely to be flexible and take a more easygoing approach.
• Lastborns may be more carefree and less rigid.

Expectations

What we expect from relationships can sometimes also be influenced by birth order.

• Firstborns often have high expectations of themselves and others, sometimes leading to criticism when people fall short.
• Middle children are more prone to seek balance in relationships and want to make sure that everyone is treated fairly and contributing equally.
• Lastborns may place the burden of responsibility on their partner's shoulders while they take a more laissez-faire approach.

"Generally, older siblings are more likely to be in the scapegoat role, while the youngest siblings often have a more idealized view of the family," Lev explains.

Other Factors Play a Role

How birth order influences interpersonal relationships can also be influenced by other factors. Some of these include personality differences, parenting styles , the parents' relationship with one another, and even the birth order of the parents themselves.

While birth order theory holds a popular position in culture, much of the available evidence suggests that it likely only has a minimal impact on developmental outcomes. In other words, birth order is only one of many factors that affect how we grow and learn. 

While some research suggests that there are some small personality differences between the oldest and youngest siblings, researchers have concluded that there are no significant differences in personality or cognitive abilities based on birth order.

Birth order doesn't exist in a vacuum. Genetics, socioeconomic status, family resources, health factors, parenting styles, and other environmental variables influence child development. Other family factors, such as age spacing between siblings, sibling gender, and the number of kids in a family, can also moderate the effects of birth order.

Adler’s birth order theory suggests that the order in which you are born into your family can have a lasting impact on your behavior, emotions, and relationships with other people. While there is some support indicating that birth order can affect people in small ways, keep in mind that it is just one part of the developmental puzzle.

Family dynamics are complex, which means that your relationships with both your parents and siblings are influenced by factors like genetics, environment, child temperament, and socioeconomic status.

In other words, there may be some truth to the idea that firstborns get more attention (and responsibility), that middleborns get less attention (and more independence), and that lastborns get more freedom (and less discipline). But the specific dynamics in your family might hinge more on things like resources and parenting styles than on whether you arrived first, middle, or last.

Individual aspects of your own personality are shaped by many things, but you may find it helpful to reflect on your own experiences in your family and consider the influence that birth order might have had.

Damian RI, Roberts BW. Settling the debate on birth order and personality . Proceedings of the National Academy of Sciences . 2015;112(46):14119-14120. doi:10.1073/pnas.1519064112

Luo R, Song L, Chiu I. A closer look at the birth order effect on early cognitive and school readiness development in diverse contexts . Frontiers in Psychology . 2022;13. doi:10.3389/fpsyg.2022.871837

Salmon CA, Daly M. Birth order and familial sentiment . Evolution and Human Behavior . 1998;19(5):299-312. doi:10.1016/S1090-5138(98)00022-1

Cundiff PR. Ordered delinquency: the "effects" of birth order on delinquency . Pers Soc Psychol Bull . 2013;39(8):1017-1029. doi:10.1177/0146167213488215

Çabuker ND, Batık HESBÇMV. Does psychological birth order predict identity perceptions of individuals in emerging adulthood? International Online Journal of Educational Sciences. 2020;12(5):164–176.

Damian RI, Roberts BW. The associations of birth order with personality and intelligence in a representative sample of U.S. high school students . Journal of Research in Personality . 2015;58:96-105. doi:10.1016/j.jrp.2015.05.005

By Kendra Cherry, MSEd Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."

Alfred Adler’s Theory of Individual Psychology and Personality

Riley Hoffman

Lab Manager at Yale University

B.A., Psychology, Harvard University

Riley Hoffman is the Lab Manager for the Emotion, Health, and Psychophysiology Lab at Yale University. She graduated from Harvard University in May 2023 with a B.A. in Psychology. In the future, Riley plans to pursue a Ph.D. in Psychology and/or law school. Her research interests lie at the intersection of psychology, health, and society.

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Saul McLeod, PhD

Editor-in-Chief for Simply Psychology

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.

Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

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Key Takeaways

• Alfred Adler’s Individual Psychology posits that humans are primarily motivated by social connectedness and a striving for superiority or success. He believed that feelings of inferiority drive individuals to achieve personal goals.
• Early interaction with family members, peers, and adults helps to determine the role of inferiority and superiority in life.
• Adler believed that birth order had a significant and predictable impact on a child’s personality, and their feeling of inferiority.
• All human behavior is goal-orientated and motivated by striving for superiority. Individuals differ in their goals and how they try to achieve them.
• A natural and healthy reaction to inferiority is compensation: efforts to overcome real or imagined inferiority by developing one’s own abilities.
• If people cannot compensate for normal feelings of inferiority, they develop an inferiority complex.
• The overarching goal of Adlerian psychotherapy is to help the patient overcome feelings of inferiority.

Individual Psychology

Alfred Adler’s school of individual school of psychology created a chasm in the field of psychology, which had been dominated by Freud’s psychoanalysis.

While Freud focused on only the internal processes — mainly sexual conflicts — that affect a person’s psychology, Adler was adamant that to fully understand a person, a psychologist must also consider other internal and external factors.

This is why he named his school of psychology individual; the word is intended to evoke a meaning of indivisibility, derived from the Latin individuum (Mosak et al., 1999, p. 6).

Alfred Adler’s Theory of Individual Psychology posits that individuals are motivated primarily by social interests and a striving for superiority or self-improvement.

Childhood experiences, especially feelings of inferiority, drive this striving, but in a healthy individual, it manifests as a desire to contribute to the welfare of others.

Maladaptive behaviors arise when this striving becomes self-centered or when inferiority feelings are overwhelming. Adler emphasized the uniqueness of the individual and the role of social connections in shaping behavior.

Compensation, Overcompensation, and Complexes

Adler thought that the basic psychological element of neurosis was a sense of inferiority and that individuals suffering with the symptoms of this phenomenon spent their lives trying to overcome the feelings without ever being in touch with reality (White, 1917)

Compensation for Weaknesses

According to Adler (2013b), all infants have a feeling of inferiority and inadequacy immediately as they begin to experience the world.

These early experiences, such as the need to gain the parents’ attention, shape the child’s unconscious, fictive goals. They give the child a need to strive towards rectifying that inferiority — a need to compensate for weakness by developing other strengths.

There are several outcomes that can occur in a child’s quest for compensation. First, if the child receives adequate nurturing and care, the child can accept his challenges, and learn that they can be overcome with hard work. Thus, the child develops “normally” and develops the “courage to be imperfect” (Lazarsfeld, 1966, pp. 163-165).

Overcompensation

However, sometimes, the process of compensation goes awry. One way in which this happens is that the feelings of inferiority become too intense, and the child begins to feel as though he has no control over his surroundings. He will strive very strenuously for compensation, to the point that compensation is no longer satisfactory.

This culminates in a state of overcompensation, where the child’s focus on meeting his goal is exaggerated and becomes pathological.

For example, Adler (1917) uses the ancient Greek figure Demosthenes, who had a terrible stutter but ended up becoming the “greatest orator in Greece” (p. 22).

Here, Demosthenes started off with inferiority due to his stutter, and overcompensated by not just overcoming his stutter, but taking up a profession that would normally be impossible for a stutterer.

Inferiority Complex

Overcompensation can lead to the development of an inferiority complex. This is a lack of self-esteem where the person cannot rectify his feelings of inferiority.

According to Adler (2013a), the hallmark of an inferiority complex is that “persons are always striving to find a situation in which they excel” (p. 74). This drive is due to their overwhelming feelings of inferiority.

There are two components of these feelings of inferiority: primary and secondary. Primary inferiority is the “original and normal feeling” of inferiority an infant maintains (Stein & Edwards, 2002, p. 23). This feeling is productive, as it motivates the child to develop.

Secondary inferiority, on the other hand, is the inferiority feeling in the adult results when the child develops an exaggerated feeling of inferiority (p. 23). These feelings in the adult are what is harmful, and they comprise the inferiority complex.

Superiority Complex

The superiority complex occurs when a person has the need to prove that he is more superior than he truly is. Adler (2013a) provides an example of a child with a superiority complex, who is “impertinent, arrogant and pugnacious” (p. 82).

When this child is treated through Adlerian therapy , it is revealed that the child behaves impatiently because he feels inferior.

Adler (2013a) claims that superiority complexes are born out of inferiority complexes; they are “one of the ways which a person with an inferiority complex may use a method of escape from his difficulties” (p. 97).

Personality Typology, or Styles of Life

Adler did not approve of the concept of personality types; he believed this practice could lead to neglecting each individual’s uniqueness.

However, he did recognize patterns that often formed in childhood and could be useful in treating patients who fit into them. He called these patterns styles of life.

Adler (2013a) claimed that once a psychologist knows a person’s style of life, “it is possible to predict his future sometimes just on the basis of talking to him and having him answer questions” (p. 100)

Adler and his followers analyze a person’s style of life by comparing it to “the socially adjusted human being” (p. 101).

Birth Order

The term birth order refers to the order in which the children of a family were born. Adler (2013b, pp. 150-155) believed that birth order had a significant and predictable impact on a child’s personality:

First-born children have inherent advantages due to their parents recognizing them as “the larger, the stronger, the older.”

This gives first-born children the traits of “a guardian of law and order.” These children have a high amount of personal power, and they value the concept of power with reverence.

Second-born

Second-born children are constantly in the shadow of their older siblings. They are incessantly “striving for superiority under pressure,” driven by the existence of their older, more powerful sibling.

If the second-born is encouraged and supported, he will be able to attain power as well, and he and the first-born will work together.

Youngest Child

Youngest children operate in a constant state of inferiority. They are constantly trying to prove themselves, due to their perceptions of inferiority relative to the rest of their family.

According to Adler, there are two types of youngest children.

The more successful type “excels every other member of the family, and becomes the family’s most capable member.”

Another, more unfortunate type of youngest child does not excel because he lacks the necessary self-confidence. This child becomes evasive and avoidant towards the rest of the family.

Only children, according to Adler, are also an unfortunate case.

Due to their being the sole object of their parent’s attention, the only child becomes “dependent to a high degree, constantly waits for someone to show him the way, and searches for support at all times.”

They also come to see the world as a hostile place due to their parents’ constant vigilance.

Critical Evaluation

As with all psychodynamic approaches to human psychology, Adlerian individual psychology receives criticism for being unscientific and difficult to prove empirically. Specifically, its focus on the unconscious fictive goal makes it arguable that Adlerian psychology is unfalsifiable.

Though Adler’s theories are difficult to definitively prove, recent neuroscience has provided some support.

A recent study summarizing modern neuroscientific evidence, and how it relates to Adlerian psychology, agreed with a statement made by Maslow in 1970:

“Adler becomes more and more correct year by year. As the facts come in, they give stronger and stronger support to his image of man” (Miller & Dillman Taylor, 2016, p. 125).

In regards to Adlerian therapy, the modern-day attitude is that while the practice is simple and easy for the layman to understand, it is flawed because it is not empirically based.

Adler’s form of counseling is criticized for its lack of depth, notably, its lack of a foundation that deals with issues not related to concepts such as birth order and early recollections (Capuzzi & Stauffer, 2016, p. 142).

How did Adler Disagree with Freud?

Adler, A. (2013a). The Science of Living (Psychology Revivals). Routledge.

Adler, A. (2013b). Understanding Human Nature (Psychology Revivals). Routledge.

Adler, A., Jelliffe, S. Ely. (1917). Study of Organ Inferiority and its Psychical Compensation: A Contribution to Clinical Medicine. New York: Nervous and Mental Disease Publishing Company.

Capuzzi, D. & Stauffer, M. D. (2016). Counseling and Psychotherapy: Theories and Interventions . Germany: Wiley.

Lazarsfeld, S. (1966). The courage for imperfection. American Journal of Individual Psychology, 22 (2).

Miller, R. & Dillman Taylor, D. (2016). Does Adlerian theory stand the test of time?: Examining individual psychology from a neuroscience perspective. The Journal of Humanistic Counseling, 55 : 11-128. doi:10.1002/john.12028

Mosak, H. H., Maniacci, M., Maniacci, M. P. (1999). A Primer of Adlerian Psychology: The Analytic-Behavioral-Cognitive Psychology of Alfred Adler . United Kingdom: Brunner/Mazel.

Stein, H. T. & Edwards, M. E. (2002). Adlerian psychotherapy. In Herson, M. & Sledge, M. H. (1st Ed.), Encyclopedia of Psychotherapy (Vol. 1, pp. 23-31). Netherlands: Elsevier Science.

White, W. A. (1917). The theories of Freud, Jung and Adler: III. The Adlerian concept of the neuroses. The Journal of Abnormal Psychology, 12 (3), 168.

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• v.112(46); 2015 Nov 17

From the Cover

Examining the effects of birth order on personality, julia m. rohrer.

a Department of Psychology, University of Leipzig, 04109 Leipzig, Germany;

Boris Egloff

b Department of Psychology, Johannes Gutenberg University of Mainz, 55099 Mainz, Germany

Stefan C. Schmukle

Author contributions: B.E. and S.C.S. designed research; J.M.R. and S.C.S. analyzed data; and J.M.R., B.E., and S.C.S. wrote the paper.

Significance

The question of whether a person’s position among siblings has a lasting impact on that person’s life course has fascinated both the scientific community and the general public for >100 years. By combining large datasets from three national panels, we confirmed the effect that firstborns score higher on objectively measured intelligence and additionally found a similar effect on self-reported intellect. However, we found no birth-order effects on extraversion, emotional stability, agreeableness, conscientiousness, or imagination. This finding contradicts lay beliefs and prominent scientific theories alike and indicates that the development of personality is less determined by the role within the family of origin than previously thought.

This study examined the long-standing question of whether a person’s position among siblings has a lasting impact on that person’s life course. Empirical research on the relation between birth order and intelligence has convincingly documented that performances on psychometric intelligence tests decline slightly from firstborns to later-borns. By contrast, the search for birth-order effects on personality has not yet resulted in conclusive findings. We used data from three large national panels from the United States ( n = 5,240), Great Britain ( n = 4,489), and Germany ( n = 10,457) to resolve this open research question. This database allowed us to identify even very small effects of birth order on personality with sufficiently high statistical power and to investigate whether effects emerge across different samples. We furthermore used two different analytical strategies by comparing siblings with different birth-order positions ( i ) within the same family (within-family design) and ( ii ) between different families (between-family design). In our analyses, we confirmed the expected birth-order effect on intelligence. We also observed a significant decline of a 10th of a SD in self-reported intellect with increasing birth-order position, and this effect persisted after controlling for objectively measured intelligence. Most important, however, we consistently found no birth-order effects on extraversion, emotional stability, agreeableness, conscientiousness, or imagination. On the basis of the high statistical power and the consistent results across samples and analytical designs, we must conclude that birth order does not have a lasting effect on broad personality traits outside of the intellectual domain.

Does a person’s position among siblings have a lasting impact on that person’s life course? This question has fascinated both the scientific community and the general public for >100 y. In 1874, Francis Galton—the youngest of nine siblings—analyzed a sample of English scientists to find that firstborns were overrepresented ( 1 ). He suspected that eldest sons enjoy special treatment by their parents, allowing them to thrive intellectually. Half a century later, Alfred Adler, the second of six children, extended the psychology of birth order to personality traits ( 2 ). From his point of view, firstborns were privileged, but also burdened by feelings of excessive responsibility and a fear of dethronement and were thus prone to score high on neuroticism. Conversely, he expected later-borns, overindulged by their parents, to lack social empathy.

Since then, empirical research on the relationship between birth order and intelligence has convincingly documented that performances in psychometric intelligence tests decline slightly from firstborns to later-borns ( 3 ), an effect that has been shown repeatedly ( 4 – 6 ) and its underlying causes investigated in depth ( 7 , 8 ) to date. By contrast, the search for birth-order effects on personality has resulted in a vast body of inconsistent findings, as documented by reviews in the 1970s and 1980s ( 9 , 10 ).

Nearly 70 y after Adler’s observations, Frank Sulloway revitalized the scientific debate by proposing his Family Niche Theory of birth-order effects in 1996 ( 11 ). On the basis of evolutionary considerations, he argued that adapting to divergent roles within the family system reduces competition and facilitates cooperation, potentially enhancing a sibship’s fitness—thus, siblings are like Darwin’s finches ( 12 ). Birth order reflects disparities in age, size, and power and should therefore determine the niches that siblings occupy within the family system. These specific adaptations to family dynamics are assumed to translate into stable personality differences between siblings that depend on birth order and can be expressed in terms of the Big Five personality traits, the standard taxonomy in psychology ( 13 ), consisting of the five broad dimensions: extraversion, emotional stability, agreeableness, conscientiousness, and openness to experience.

According to Sulloway’s theory, firstborns, who are physically superior to their siblings at a young age, are more likely to show dominant behavior and therefore become less agreeable. Later-borns, searching for other ways to assert themselves, tend to rely on social support and become more sociable and thus more extraverted. * Siblings compete for scarce resources, and parental favor can be a crucial part of survival. Firstborns try to please their parents by acting as surrogate parents for their siblings, a behavior that can increase conscientiousness. Predictions for imagination and intellect, both subdimensions of the Big Five trait openness to experience ( 14 ), tend to differ. Later-borns are constrained to finding an unoccupied family niche through exploration and therefore score higher on imagination. Firstborns perform better on psychometric intelligence tests and correspondingly score higher on intellect, a self-reported trait correlated with objectively measured intelligence ( 15 ). Finally, no birth-order effects on overall emotional stability were assumed ( 12 ). However, for specific emotional stability items, Sulloway ( 15 ) had predicted firstborns to be more anxious and quicker to anger, and later-borns to be more depressed, vulnerable, self-conscious, and impulsive.

Sulloway first supported his framework by analyzing the social attitudes and birth-order positions of historical figures (ref. 11 ; but see ref. 16 ). Later, Sulloway’s hypotheses about personality were confirmed by several empirical studies ( 12 , 15 , 17 ). Nevertheless, a considerable number of other studies have supported only part of his hypotheses or have not found any birth-order effects at all ( 18 – 22 ). Paulhus ( 23 ) suggested that these conflicting findings may be due to different research designs: Studies comparing individuals from different families (between-family design) supposedly lack the power to detect subtle effects on personality because large parts of the variance in personality are not caused by birth order, but by variables such as socioeconomic status and genetic predispositions. A more powerful design compares siblings from the same families who are matched on many of these potential confounding variables and share a considerable number of genes. Indeed, all studies that confirmed Sulloway’s hypotheses ( 12 , 15 , 17 ) applied a within-family design. However, all of these studies also assessed sibling personality in a convenient, but potentially problematic, way because ratings were collected from only one sibling per family, who rated him/herself and his/her siblings at the same time. Existing beliefs and stereotypes about birth order ( 24 ), as well as contrast effects, could easily skew such ratings. To test whether birth order has a profound impact on personality, independent assessments of each sibling’s personality should be compared. To our knowledge, only one study has actually used independent ratings of the Big Five in a within-family design thus far ( 21 ), and it found no birth-order effects. However, this finding may be the consequence of low power because the sample comprised only 69 sibling pairs.

The current study aims to settle the debate on the systematic impact of birth order on personality by overcoming all of these limitations. Specifically, ( i ) only data with an independent assessment of siblings’ personality were used; ( ii ) multiple large national panels were combined to acquire data that would be sufficient to test even small birth-order effects with adequate power; and ( iii ) birth-order effects on personality were tested by using both within- and between-family designs. As explained above, between-family designs are inherently less powerful, but not useless per se: According to the law of large numbers, the results of both analytical approaches should converge with increasing sample size. We therefore expected the results from the between- and within-family analyses to be consistent.

The data came from the National Child Development Study (NCDS; Great Britain; refs. 25 and 26 ), the National Longitudinal Survey of Youth 1997 Cohort (NLSY 97; United States; ref. 27 ), and the Socio-Economic Panel (SOEP; Germany; refs. 28 and 29 ). All panels included self-report personality inventories and measures of intelligence.

Changes in personality over time—e.g., becoming more conscientious with increasing age ( 30 )—are inherently confounded with birth order, a problem that is especially evident in a within-family design: Firstborns are, of course, always older than their later-born siblings, and this fact can cause spurious associations between birth order and personality. To rule out age effects in the NLSY and SOEP samples, we converted the personality variables into age-adjusted T scores ( M = 50, SD = 10) and the results of the intelligence tests into age-adjusted intelligence quotient (IQ) scores ( M = 100, SD = 15). It was not necessary to control for age in the NCDS sample because all participants were of the same age.

Another potential confounding variable is sibship size. There are more later-borns in larger sibships. Hence, differences between first- and later-borns might emerge because later-borns are more likely to be born into families with a lower socioeconomic status, which can in turn be associated with differences in intelligence and personality. For this reason, we controlled for the effects of sibship size in all between-family analyses. Because there should be no association between birth-order position and parental socioeconomic status beyond what is explained by sibship size, additional control for parental socioeconomic status was deemed unnecessary. Finally, within-family analyses did not require statistical control for sibship size because they only compare individuals from the same sibship. Individuals from families with more than four siblings were excluded from the analyses because they made up only a small part of the sample (<11%), leading to insufficient power to detect the subtle effects that would have been expected. Between-family ( n = 17,030) and within-family ( n = 3,156) analyses were performed on nonoverlapping samples (see Table S1 for details of the sample sizes).

Number of participants included in the between and within-family analyses by panel, sibship size, and birth-order position

We first examined the effects of birth order on intelligence by using between-family analyses in each of the three panels, as well as in the combined sample. These analyses revealed the expected decline in IQ scores from first- to later-borns both for the combined sample ( Fig. 1 A ) and for each separate panel ( Table 1 ). This birth-order effect was also found in the within-family analyses ( Fig. 2 A and Table 1 ). The observed effect of ∼1.5 IQ points (i.e., 10% of a SD) for each increase in birth-order position is in line with previous findings ( 3 – 6 ). To illustrate this small effect, in our between-family sample of sibships of two, a randomly picked firstborn had a 52% chance of having a higher IQ than a randomly picked secondborn; conversely, a secondborn had a 48% chance of having a higher IQ than a firstborn. The effect was more prominent in our within-family sample due to the greater similarity of siblings from the same family: In sibships of two, the older sibling had a higher IQ than his or her younger sibling in 6 of 10 cases. This replicated finding not only underlines the robustness of birth-order effects on intelligence, but also indicates that our samples and analytical strategies were appropriate for detecting existing birth-order effects.

Effects of birth order position and sibship size on personality and intelligence. Mean scores and 95% confidence intervals are displayed for intelligence ( A ) and personality ( B – H ), depending on sibship size and birth-order position in the combined between-family sample that included the NCDS, NLSY, and SOEP participants. Personality variables were standardized as T-scores with a mean of 50 and SD of 10; intelligence was standardized as an IQ score with a mean of 100 and SD of 15. Birth-order effects were significant for intelligence, openness to experience, and intellect ( Table 1 ). ( B – H ) Personality traits were as follows: extraversion ( B ), emotional stability ( C ), agreeableness ( D ), conscientiousness ( E ), openness to experience ( F ), imagination ( G ), and intellect ( H ).

Tests of statistical significance for effects of birth-order on intelligence and personality

The sample sizes used in these analyses varied between 2,914 and 17,030 for the between-family analyses and between 1,094 and 3,156 for the within-family analyses. See Table S1 for the specific sample sizes.

Effects of birth-order position and sibship size on personality and intelligence. Predicted mean scores from fixed-effects regressions and 95% confidence intervals are displayed for intelligence ( A ) and personality ( B – H ) depending on sibship size and birth-order position in the combined within-family sample that included the NLSY and SOEP participants. Birth-order effects were significant for intelligence and intellect ( Table 1 ). ( B – H ) Personality traits were as follows: extraversion ( B ), emotional stability ( C ), agreeableness ( D ), conscientiousness ( E ), openness to experience ( F ), imagination ( G ), and intellect ( H ).

Our main analyses for investigating the relationship between birth-order position and personality led to consistent results for four of the Big Five personality traits. Birth-order position had no significant effect on extraversion, emotional stability, agreeableness, or conscientiousness in the between-family analyses or in the within-analyses ( Figs. 1 B – E and 2 B – E ; Table 1 ). We confirmed these nil effects by conducting separate analyses for each of the three panels ( Table 1 ). We additionally analyzed each of the three sibship sizes separately. Tables S2 – S5 show the mean scores and detailed results by panel and sibship size of all between- and within-family analyses. Again, birth-order position had no consistent effect on any of these four personality traits. An additional analysis of specific emotional-stability items on which opposing birth-order effects were hypothesized by Sulloway ( 15 ) also yielded no significant results ( Tables S3 and ​ andS4 S4 ).

Mean scores and results of between-family analyses (NCDS, NLSY, and SOEP) and within-family analyses (NLSY and SOEP)

Mean scores and results of between-family analyses (NCDS participants)

Mean scores and results of between- and within-family analyses (NLSY participants)

Mean scores and results of between- and within-family analyses (SOEP participants)

In the within-family sample of the SOEP, there were not enough individuals with information on IQ ( n = 141) to conduct meaningful analyses, given the small effect sizes that were expected.

Regarding openness to experience, the fifth of the Big Five personality traits, our predictions differed for the subdimensions of intellect and imagination. Accordingly, we decomposed openness into intellect and imagination in the NCDS and the SOEP. Decomposition was not possible in the NLSY because the openness scale that was used did not contain any items that measured intellect. Whereas we observed no birth-order effects on imagination, we found significant effects on intellect in both the between- and within-family analyses ( Figs. 1 G and H and 2 G and H ; Table 1 ). We observed a decline in intellect of ∼1 T score (i.e., 10% of a SD) for each increase in birth-order position, an effect that is comparable in magnitude with the IQ effect. As a consequence of the different proportions of intellect items on the openness scales in the three samples, the analyses of the global openness to experience scale led to inconsistent results: Our analyses revealed a significant effect on openness to experience in the combined between-family sample ( Fig. 1 F ), but panel-specific analyses showed that this effect was mainly driven by the NCDS sample and that this effect was not observable in the NLSY sample at all ( Table 1 ).

The items used to measure intellect (e.g., NCDS, “I am quick to understand things”; SOEP, “I am someone who is eager for knowledge”) can be understood as an indirect measure of self-estimated intelligence. This idea was bolstered by the correlation between IQ scores and intellect in our study ( r = 0.32, P < 0.001, in the combined between-family sample), a finding that matches meta-analytical findings on the correlation between self-estimated and objectively measured intelligence ( 31 ). To test whether the birth-order effect on self-reported intellect merely reflects differences in IQ scores, we reran the analysis on intellect, this time including IQ scores as a covariate. The effect on intellect slightly decreased in magnitude, but retained its significance, indicating that there is a genuine birth-order effect on intellect that goes beyond objectively measured intelligence ( Table S6 ).

Intellect scores before and after adjusting for intelligence (IQ) and results of corresponding between-family analyses (NCDS and SOEP participants)

In the NLSY, we were not able to decompose openness to experience into imagination and intellect due to the content of the questionnaire. Furthermore, we were not able to investigate whether the effect on intellect persisted after adjustment for IQ in a within-family design, because ( i ) in the NCDS there was no within-family data included due to the design of the study; and ( ii ) in the within-family sample of the SOEP were not enough individuals with information on IQ ( n = 141).

Previous research has frequently focused on differences between first- and later-borns, instead of distinguishing between all birth positions within a given sibship size. To test the robustness of our results, we recoded birth order to distinguish between first- and later-borns and reran both the between- and within-family analyses. The results were in line with the results of our previous analyses: Firstborns scored slightly higher on intelligence and intellect, but we observed no differences in extraversion, emotional stability, agreeableness, conscientiousness, or imagination ( Table S7 ). One might also assume that middle children experience less uniform birth-order effects because their position within the family changes over time. We therefore reran the between-family analyses with only the first- and last-born individuals, again replicating previous analyses ( Table S8 ).

Mean scores and results of between-family analyses (NCDS, NLSY and SOEP) and within-family analyses (NLSY and SOEP) comparing first- and later-borns

Mean scores and results of between-family analyses comparing first- and last-borns (NCDS, NLSY, and SOEP participants)

Within-family analyses comparing only first- and last-borns were not feasible for sibships with more than two siblings because of the small sample of only 130 sibling pairs. For sibships of two, these analyses are equivalent to the within-family analyses presented in Tables S2 and ​ andS7 S7 .

Beer and Horn ( 32 ) suggested that prenatal hypomasculinization of later-born males might lead to specific birth-order effects in pairs of male siblings: Later-borns are expected to show more female traits. To rule out the possibility that mixed or female sibships obscure such effects, we separately analyzed sibships consisting of two sisters and two brothers. The between-family analyses revealed—besides the already identified birth-order effects on intelligence and intellect—only one significant effect on the Big Five personality traits. Second-born children in male sibships of two scored higher on conscientiousness than firstborns, but this effect was not found in the within-family analyses and went counter to the predictions made by the Family Niche Theory (see Table S9 for both analyses). We thus found no support for the notion that birth-order effects on personality would be more visible in male sibships.

Mean scores from sibships with two children of the same sex and results of the corresponding between and within-family analyses (NLSY and SOEP participants)

The NCDS sample could not be included in this analysis because it was missing information on siblings’ sex. We did not present results for families with one male and one female sibling because birth-order effects would be confounded with gender effects in these analyses.

Finally, following the claim by Healey and Ellis ( 33 ) that selecting siblings with an age gap ranging from 1.5 to 5 y provides a better test of birth-order effects, we limited our analyses to sibships in which all age gaps between consecutive siblings fell within this range. Even though the sample sizes were still high in comparison with earlier studies—with >1,600 individuals in the within-family analyses and >5,600 individuals in the between-family analyses—we again found effects on only intelligence and openness, the latter completely attributable to the subdimension intellect ( Table S10 ).

Mean scores and results of between and within-family analyses after restricting the analyses to families in which all age gaps between consecutive siblings were within the range of 18–60 mo (NLSY and SOEP participants)

The NCDS sample could not be included in this analysis because it was missing information on the age gaps between siblings.

All in all, we did not find any effect of birth order on extraversion, emotional stability, agreeableness, conscientiousness, or imagination, a subdimension of openness. There was a small, but significant, decline in self-reported intellect, a second subdimension of openness. The effect on intellect persisted after controlling for IQ scores, indicating that there is a genuine birth-order effect on intellect that goes beyond objectively measured intelligence and can be observed in adults. † Zajonc and Markus ( 7 ) proposed that older siblings profit intellectually from being “teachers” to their younger siblings—a process that might also account for differences in intellectual self-concept and -estimation when children internalize their roles as “teachers” or “students.” Social comparison ( 34 ) among siblings during childhood and adolescence might be another process that specifically contributes to differences in self-estimated intelligence: Individuals may evaluate their own intellectual abilities in relation to their siblings—and this evaluation may lead to favorable outcomes for firstborn children because of their developmental advantage. This comparison could cause a stable bias in self-estimations of intelligence, with later-born children slightly underestimating and firstborn children slightly overestimating their actual cognitive abilities. These ideas are compatible with a competitive niche partitioning theory within the family, where role differentiations and shared beliefs might lead to birth-order effects on self-rated intellect that go beyond objectively measured intelligence ( 11 , 12 ). Another interesting issue supporting partially independent determinants of effects on IQ scores and intellect is the finding that increasing sibship size negatively influences only IQ scores, but not intellect ( Table S2 ). It remains a promising issue for future research to disentangle common and unique sources that influence self-estimated and objectively measured intelligence within the family system.

Our results emerged consistently in all three panels included in this study—i.e., they were replicated across three different nations, across different measures of personality and intelligence, and by assessing individuals in early adulthood (NLSY), at age 50 (NCDS), and across the whole life span (SOEP). Furthermore, results were unaffected by the choice of analytical strategy, emerged consistently in the between- and within-family analyses and for both sexes, and were corroborated by the results of several control analyses. On a methodological note, the consistent effects found for intellect demonstrate that, not only IQ measures, but brief self-report measures are also generally sensitive to detecting birth-order effects when such effects indeed exist.

Thanks to our large sample size, we achieved a power of 95% with which to detect a mean difference as subtle as 5% of a SD between first- and later-borns in our between-family analyses of personality. Furthermore, a post hoc analysis revealed that we achieved a power of >99% with which to detect effects in the size of the typical IQ score difference of 1.5 points between first- and later-borns.

With regard to the high power and the consistent pattern of results, we must conclude that birth order does not have a meaningful and lasting effect on four of five of the broad personality domains and only partly on the fifth. Thus, with the exception of intellect, the central predictions of the Family Niche Theory with regard to personality could not be confirmed by our analyses. Of course, this general conclusion does not necessarily imply that there are no specific circumstances in which birth-order effects outside of the intellectual domain might emerge.

For example, Harris proposed that birth-order effects could be visible within the family, but might not affect behavior and relationships outside of this context (ref. 35 ; see also ref. 36 ). Furthermore, birth order might primarily or exclusively affect parts of the personality system that are not accessible to self-insight or that are masked by socially desirable responding in self-reports. This hypothesis can be addressed by using other reports ( 17 , 18 , 36 ) or behavioral observations of personality, both of which were not included in the panels used in our samples. Other research questions include whether birth-order effects emerge ( i ) only in larger sibships, which are now rare, such as the ones that Galton and Adler grew up in; ( ii ) only when investigated in more specific personality dimensions (e.g., sensation-seeking or risk-taking); or ( iii ) in different cultures (our analyses were based on data from industrialized nations of the Western world). However, the predictions made by the Family Niche Theory that we tested in this study were not limited to specific contexts and were based on mechanisms that were not restricted to specific cultures. Birth-order effects under the constraints named above would call for a refinement of the theoretical framework explaining their emergence.

To conclude, birth-order position seems to have only a small impact on who we become. Both the already-documented effect on objectively measured intelligence and the previously unidentified effect on self-reported intellect found in the present study were statistically significant, but small (at ∼10% of a SD), in terms of conventional effect sizes. Whether these differences among siblings matter at the individual level (e.g., despite the average decline in IQ, the second-born of a sibling dyad will still be smarter than his or her older sibling in 4 of 10 cases) is certainly a subject for further debate (see ref. 37 for arguments that these differences are important). The main message of this article, however, is crystal clear: On the basis of the high power and the consistent results found across samples and analyses, it can be concluded that birth order does not have a meaningful and lasting effect on broad Big Five personality traits outside of the intellectual domain.

Materials and Methods

Description of the panels..

The NCDS ( 25 , 26 ) originated from the Perinatal Mortality Survey 1958 and tracks the life courses of all individuals born in Great Britain in 1958 in a particular week. The study is managed by the Centre for Longitudinal Studies and funded by the Economic and Social Research Council. The NLSY 97 ( 27 ) conducted by the US Department of Labor’s Bureau of Labor Statistics consists of a representative sample of US residents born during the years 1980–1984. Data collection for this panel study began in 1997 and included all household members between 12 and 16 y of age from randomly selected households. The SOEP ( 28 , 29 ) is a representative panel study of private households and their members in Germany. It began in 1984 and has since been refreshed several times to ensure representativity. The study is located at the German Institute for Economic Research (DIW Berlin). Our study did not require ethical approval because we analyzed existing and fully anonymous data; informed consent was obtained from participants by the respective institutions.

Assessment of Birth Order and Sibship Size.

In each sample, a proxy for social birth position was derived from available information about siblings and household composition in youth. We decided to focus on the individual’s position among the children within the household instead of biological sibling status because the expected birth-order effects on personality are supposed to stem from social rather than biological processes. In most cases, however, social birth-order position equals biological birth-order position. Furthermore, we excluded participants who were only children because they cannot be compared with any siblings and are thus uninformative for the analysis of birth-order effects. We also decided to exclude twins because they grew up in a very specific sibling configuration that likely obscures the birth-order effects hypothesized by the Family Niche Theory. In particular, twins compete for resources and family niches not only with their older and/or younger siblings but also with their other twin of the same age. Participants from households with a sibship size exceeding four children also were not included in our analyses, because they represented <11% across the three samples and therefore did not enable reliable analyses of larger families. Table S1 shows the final sample sizes.

Birth-order position was derived from the parental questionnaires administered in 1965 and 1969. The respondent entered the total number of children in the household under the age of 21, as well as the target child’s position among these children. For all participants included in our analyses, information about household composition was available for both years of assessment. We equated the stated number of children in the household with the variable “sibship size” and the position among those children with “birth-order position” when there was no change in those variables between the target’s age of 7 and the age of 11. Whenever data from the two assessments indicated regular family dynamics (i.e., younger children “appearing” or older children “disappearing” between 1965 and 1969), we considered these changes when determining the “sibship size” and “birth-order position” by including both siblings who were newly born between 1965 and 1969 and older siblings who moved out between 1965 and 1969. Cases with data indicating patchwork-family dynamics (i.e., younger children disappearing from the household or older children appearing) were dropped from further analysis.

Birth-order position was derived from data on household members and nonresidential relatives gathered in 1997. All household members marked as full, half, step, or adoptive siblings living in the household of origin in 1997 were included in the computation of birth-order position. Nonresidential full siblings were also included as long as they were older than the target because it was likely that the target and said sibling had lived together previously. An age comparison was then used to determine the target’s birth-order position. Because all household members within the targeted age range of 12–16 y were interviewed, in some cases, we had data from two or more siblings from one family. Data on these siblings were used in our within-family analyses, and the other participants were used in our between-family analyses, hence ensuring that the within- and between-family datasets were completely nonoverlapping.

Birth-order position was derived from a number of questions about siblings included by the SOEP for the purpose of the present study and asked in 2013. Full, half, step, and adoptive siblings were counted toward sibship size as long as targets reported having spent the first 15 y in the same household. Targets who reported having spent at least 1 y, but fewer than 15 y, with one or more siblings were dropped to exclude patchwork families. An age comparison was then used to determine the target’s birth-order position. Because all household members are included in the SOEP after they turn 17, in some cases, we had data from two or more siblings from one family. Data from these siblings were used in our within-family analyses, and the other participants were used in our between-family analyses, hence ensuring that the within- and between-family datasets were completely nonoverlapping.

Assessment of Personality.

Personality was assessed in 2008 at age 50. Participants completed a set of 50 items from the international personality item pool ( 38 ) to measure the Big Five personality traits. Scales were computed if at least 9 of 10 items were answered for each of the five traits. We conducted a principal axis factor analysis with oblimin rotation on the 10 items, measuring openness to experience, extracting two correlated factors ( r = 0.65). On the basis of the results of this factor analysis and supported by content-related considerations, we attained a five-item measure of self-reported intellect (“I use difficult words,” loadings on the two factors of 0.58/0.00; “I have a rich vocabulary,” 0.55/0.07 ; “I am quick to understand things,” 0.32/0.23; and, reverse-coded: “I have difficulty understanding abstract ideas,” 0.68/0.04; “I am not interested in abstract ideas,” 0.60/0.00) and a five-item measure of imagination (“I am full of ideas,” −0.01/0.74; “I have excellent ideas,” −0.03/0.71; “I have a vivid imagination,” 0.05/0.48; “I spend time reflecting on things,” 0.05/0.22; and, reverse-coded: “I do not have a good imagination,” 0.10/0.45). Last, we generated two measures, each consisting of two items from the emotional stability scale on which firstborns (“I get upset easily” and “I get irritated easily”) and later-borns (“I often feel blue,” and, reverse-coded: “I seldom feel blue”) were hypothesized to score higher according to Sulloway ( 15 ). All scores were converted into T scores ( M = 50; SD = 10) on the basis of the NCDS sample.

Personality was assessed in 2009 (age 29–35). Participants completed the Ten-Item Personality Inventory ( 39 ) consisting of two items for each Big Five dimension. Scales were computed if no items were missing. The item “I see myself as: anxious, easily upset” from the emotional stability scale was furthermore analyzed separately to test Sulloway’s hypothesis that firstborns score higher on this specific item ( 15 ). The two items used to measure openness to experience in the NLSY—“I see myself as: open to new experiences, complex” and “…conventional, uncreative”—could not be decomposed any further because they both measure the imaginative component of openness. To control for potential nonlinear age effects, we locally regressed each of the Big Five traits as well as the specific item on age in the NLSY sample, by using the LOWESS procedure with a bandwidth of 0.5. We then converted the residuals from these regressions into T-scores, which reflect personality scores after adjusting them for normative age trends.

Personality was assessed in 2013 (age 18–98). Participants completed a version of the BFI-S ( 40 ) containing 16 items, including 4 items for openness and 3 for each of the remaining Big Five personality traits. We split the items measuring openness to attain a three-item measure of imagination (“I am someone who… is original, comes up with new ideas,” “…values artistic, aesthetic experiences,” and “…has an active imagination”), and used the fourth item as a measure of intellect (“…is eager for knowledge”). Scales were computed if no items were missing. Local regression was used to attain age-adjusted T-scores as described for the NLSY.

Assessment of Intelligence.

Intelligence was assessed in 1969 (age 11). The children were individually tested by teachers with a General Ability Test consisting of 40 verbal and 40 nonverbal items ( 41 ). We generated IQ scores ( M = 100; SD = 15) from the sums of the scores of the two subtests.

Intelligence was assessed in 1997 and 1998. Respondents participated in the computer-adaptive form of the Armed Services Vocational Aptitude Battery ( 42 ). We calculated IQ scores from the age-sensitive summary percentile score using 59 items. The resulting scores had a slightly lower mean ( M = 98.44) because the calibration sample tended to score higher than the NLSY97 sample.

Intelligence was assessed in 2013 with the MWT-B, a multiple-choice vocabulary test with 37 items ( 43 ). Using the same local regression procedure as used for the NLSY and SOEP personality scores, we calculated age-adjusted IQ scores from the number of correct answers.

Statistical Models.

Between-family analyses..

We ran separate ordinary least-squares regression analyses for each of the personality dimensions and intelligence. Three factor variables were entered into the model as predictors: birth-order position, sibship size, and data source. Birth-order position was coded in a way that distinguished between each position within a sibship from firstborn to fourth-born and was represented in the model by three dummy variables. This way, we were able to estimate the unique effect of each position on personality rather than only the overall linear effect. Similarly, sibship size (two to four) and data source (NCDS, NLYS, SOEP) were each represented by two dummy variables. We decided to report the results of aggregated analyses in the main table to ( i ) attain a number of results that would be easier to communicate, ( ii ) increase the power of the analyses and, ( iii ) prevent alpha accumulation. However, aggregating individuals from different sibship sizes also had the potential to be problematic: ( i ) The design inherently comprised empty cells—for example, there was no third-born in a family with only two children—and ( ii ) our coding was based on the assumption that, for example, second-born children in a family of two fall into the same birth-order category as second-born children in a family of three. To avoid these problems, we also analyzed birth-order effects separately for each sibship size.

Within-family analyses.

We ran fixed-effects regression models ( 44 ) to estimate within-family birth-order effects separately for each of the personality dimensions and intelligence. Birth-order position was entered as a factor variable, coded as described for the between-family analyses. Additional factor variables to control for data source and sibship size were not necessary: The fixed-effects regression estimates the within-effects by comparing only individuals from within a family who share their sibship size and are part of the same panel study.

Acknowledgments

The National Child Development Study (NCDS) data were made available by the Centre for Longitudinal Studies at the Institute of Education, University of London, and the UK Data Service. The National Longitudinal Survey of Youth (NLSY) data were made available by the U.S. Bureau of Labor Statistics. The Socio-Economic Panel (SOEP) data were made available by the German Institute for Economic Research (DIW). We thank these institutions for providing these datasets.

The authors declare no conflict of interest.

Data deposition: All data used in this study are publicly available to scientific researchers. The NCDS data are available from the UK Data Service, ukdataservice.ac.uk ; the NLSY97 data from the US Bureau of Labor Statistics, www.bls.gov/nls ; and the SOEP data from the German Institute for Economic Research (DIW), www.diw.de/en/soep . To achieve full transparency and to allow the reproducibility of our analyses, the scripts for replicating our data analysis are archived in the Open Science Framework, https://osf.io/m2r3a .

This article is a PNAS Direct Submission. C.F.C. is a guest editor invited by the Editorial Board.

*Sulloway postulated an opposing effect of birth order on dominance as a facet of extraversion ( 15 ). However, because the extraversion items in the questionnaires used in this study did not include the dominance facet, we were unable to test this additional hypothesis.

† Parental age might be a potential confounding variable that is causing the effects on intelligence and intellect. For example, a higher paternal age at conception carries the risk of a higher number of new genetic mutations that might lower intelligence in later-borns. Assuming this kind of process, one would expect that spurious birth-order effects caused by differences in parental age would become larger with increasing age gaps between siblings. We tested this possibility by including the difference in age between the target person and firstborn as an additional predictor in our between- and within-family analyses of intelligence and intellect. Age differences did not significantly explain any variance above and beyond birth-order position in any of these four analyses (all P > 0.52). This result suggests that parental age is not the driving force behind the effects on intelligence and intellect.

See Commentary on page 14119 .

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1506451112/-/DCSupplemental .

Birth Order and Its Influence on Personality Essay

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Birth order is defined as a person’s rank by the sequence of birth among his or her siblings. Birth order is commonly believed to have a profound and lasting effect on psychological development.

Sulloway (1995, 1996), states that first-born siblings are expected to be rated higher on the characteristic trait of dominance whereas siblings who are younger or born later can be rated higher on the sociability aspect.

The concept of ‘birth-order’ considerably influencing the personality of a being is not a novel phenomenon. Way back in 1874, Sir Francis Galton (Galton, 1874) proposed that renowned male scientists had a greater possibility to be ‘first-borns’ in their family units rather than ‘later-born’ (Forer, 1969). Investigation and study have revealed that individuals who are born first are found in larger numbers in political office (Hudson, 1990). Zajonc, (2001) reveals that there are likely to be birth-order variation in the levels of intellect along with the ‘Big Five’ facets of character including extraversion, anxiety, meticulousness, amicability, and naivety to experience (Paulhus, Sulloway 1996, Trapnell & Chen 1999).

Sulloway (1996, 2001) has suggested a representation of family unit dynamics relating to the results of birth-order in the character and conduct, which has varied ‘‘causal mechanisms’’. In support of this, Sulloway proposes that whilst parental income is inadequate, the parents tend to focus the available resources more profoundly on a single child, usually the one who is born first. Furthermore, Sulloway infers that first-borns are better built and tougher than those born subsequently and thereby employ these competitive physical features tremendously to their benefit.

Further ‘causal mechanisms’ incorporate ‘de-identification’, where children seek to discriminate themselves from each other another with respect to significance, societal approach, individuality, and role demarcation when sometimes, brothers and sisters implement special characteristics in the families for example, “the rebel of the family”, or “the lamb of the family”, so as to lessen rivalry (Sulloway, 1996, 2001).

Then experimental verification to sustain this model of family dynamics has primarily originated from Sulloway’s (1996) ‘meta-analysis’ of one hundred and ninety six studies involving birth-order. Maintaining the hypothesis, first-born position affirmatively allied to meticulousness, anxiety, and assertiveness, whereas the category of later-born absolutely connected with amicability and ingenuousness to experience.

Sulloway further elucidated these results by proposing that first-borns have a greater propensity to accepted by parents and have great enthusiasm to fulfill parental hopes. Moreover, he states that, first-borns tend to be additionally forceful and envious so as to safeguard cherished parental assets. Sulloway further reveals that later-born children, in contrast, have a greater probability to be pleasant to facilitate the decrease of any potential hostile conflicts with their elder siblings.

Jefferson et al., (1998) too found outcomes corresponding to Sulloway’s calculations in a study conducted by him, permitting the friends, neighbors or co-workers to rate the participants instead of the participants evaluating themselves. Keeping in line with the earlier results, later-borns were recognized by their peers as displaying characteristics which were more friendly, pioneering and reliant than their first-born siblings.

Alfred Adler (1870-1937) who was an Austrian psychiatrist was among the foremost theorists proposing that birth order impacts the individuality of a person. He debated that the order in which a child is born has the potential to significantly alter the lifestyle of a person which involves several facets of the personality such as companionship, love, occupation and many other aspects of life. Adler proposes that when a second child is born, the firstborns are ‘dethroned’, thereby having the potential of influencing them permanently as younger siblings and single children are sometimes pampered.

Michael E. Lamb and Brian Sutton-Smith, elucidate the fact that relationships between siblings habitually remain for an entire life span in their book ‘Sibling Relationships: Their Nature and Significance across the Lifespan’ . They highlight the ‘lifespan’ term proposing that progress within relationships is an incessant process and birth-order affects the lifelong process of development of the personality of an individual (Jefferson et al.1998) and as such research has indicated that unification of persons with dissimilar birth orders tend to be steadier than those of persons of the same birth order (Leman 1998, Toman 1976).

A Greek study affirmed that among individuals at the low birth order there is an increased risk for divorce, and debated that this consequence was predominantly apparent among single children (Skalkidou 2000).

The reason why partners’ birth order is likely to impact matrimonial strength is due to the effect of birth position of either spouse which consequently affects the personality and its development process, thereby producing specific traits in individuals bringing variations in their compatibility to others.

First-borns are likely to be dominating individuals and the subsequent unification of two individuals of the same dominating order, presents a greater likelihood of a divide. The same rule would apply to the union of two last born individuals who are likely to have comparatively unsteady relationships (Leman 1998, Toman 1976).

The reasons why birth order of individuals has the potential of affecting divorce rates is primarily due to the fact that individuals may have specific traits in their personalities such as a poorer levels of risk avoidance which may perhaps influence marriage termination pace. Personalities are known to be affected by birth order because the relations of parents with children is diverse and is to a great extent impacted by the birth order of the siblings (Ernst and Angst 1983), as a result of which dissimilar birth orders can stimulate parents to socialize in dissimilar ways with their children.

Influence of birth order in understanding of the different scientists

According to Eisenman (1992), first-borns are extra apprehensive, superior accomplishers and more innovative, resulting their lives to be extremely dissimilar merely because of them being born as a first child in the family. This may attribute to the fact that a majority of parents tend to be excessively concerned for their first children, and also may possibly be more restraining with him or her than with children born later. It is this theory that elucidates the higher risk of divorce among marriages between first-borns, because restriction is certainly interrelated with an annulment threat (Jockin et al. 1996).

Moore et al. (1997), who researched thirty nine mothers and their first and second born children of two months of age, found that mothers tend to positively influence their second-born children as compared to the first-borns, consequently resulting in the second rank children to develop a more positive personality than the first born rank.

Obviously, this behavioral difference can affect the risk of divorce given the fact that positivism and negativity in emotions are directly correlated to potential divorce risks (Jockin et al. 1996).

We can thus safely conclude that birth-order does have effects on the individual personality development and the primary aspects of extraversion, friendliness and domination, vary in relation to birth-order (Jefferson et al.,1998).

Beer and Horn (2000), implemented an innovative approach by researching a sample of adopted children, and found a similarity in proved results emphasizing that first-reared children do have an elevated intensity of meticulousness. Behavioral patterns in individuals are firmly fashioned in childhood with the profound influence of parents and siblings and therefore are likely to affect marriage stability in the life of individuals. Children who are born first along with single children have a greater likelihood of developing particular characteristic qualities, including anxiety and aspiration, resulting a child who is a first born to develop a steadier relationship with a potential later-born having dominating aspects in the persona.

However, in the case of both the marital partners being first-borns, potentially implies a higher level of conflict given that both may reflect qualities of being stubborn or less compromising behaviors. For instance, if either partner is a first-born individual, and the other is a later-born, the resultant relationship is likely to be steadier in view of the “leader-follower” kind of union, where one partner is less dominating than the other, thereby reducing the chances of disagreement between them. In the dissimilar case of both the marital partners being later-born individuals, there may be an absence of a leader in the relationship, resulting in an unsatisfying relationship between the two.

Thus we see how there is an effect of birth order on divorce risk. It is evident that single children run a lower risk of dissolving their marriages. Marriages between two first-borns are the most unstable relationships, whereas marriages between two only children are the most stable.

Ever since the 1970s, the ‘confluence model’ of Robert Zajonc has been significant in elucidating one of the most important hypothesis to explicate why firstborn children or individuals habitually achieve better scores for their intellect and accomplishment tests than other children. According to the model, firstborn children early on in their lives, primarily have greater adult authority surrounding them and as a result, they spend their preliminary childhood years intermingling in a scholarly environment. This theory also proposes that firstborn children tend to be more intelligent than ‘only children’, because ‘single children’ cannot benefit from the ‘tutor effect’ of elder siblings teaching the younger ones.

According to recent researchers conducted and reported in the journal Science (June 2007), “the eldest children in families tend to develop slightly higher IQs than their younger siblings” (Harris, Judith Rich, 2006). These results could possibly be an outcome of the valuable quality time that parents tend to spend with their children who are born first rather than those who are born later. (Price, Joseph, 2008)

The discussion as to whether birth-order affects the personality development of an individual is in no way over and expectantly new researchers will explore fresh perspectives and means in the birth-order research.

Adler, A. (1964). Problems of neurosis . New York: Harper and Row.

E. Beck et al. / Personality and Individual Differences.

Eisenman, R. 1992. Birth order, development and personality. Acta Paedopsychiatr. 1992;55(1):25-7.

Jockin V, M. McGue and D. Lykken (1996): Personality and divorce: a genetic analysis.

Ernst, C., & Angst, J. 1983. Birth order: Its influence on personality. Berlin: Springer-Verlag.

Forer, L. K. (1969). Birth-order and life roles. Illinois: Charles C. Thomas.

Galton, F. (1874). English men of science: Their nature and nurture. London: Macmillan.

Harris, Judith Rich (2006), No Two Alike: Human Nature and Human Individuality (pp. 107-112)

Hudson, V. M. (1990). Birth-order of world leaders: an exploratory analysis of effects on personality and behaviour. Political Psychology, 11, 583–601.

Jefferson, T. J., Herbst, J. H., & McCrae, R. R. (1998). Associations of birth-order and personality traits: evidence from self-reports and observer ratings. Journal of Research in Personality, 32, 498–509.

Lamb, M. E., Sutton-Smith, B. (1982). Sibling Relationships: Their Nature and Significance of the Lifespan. Lawrence Erlbaum Associates.

Leman, K. 1998. The New Birth Order Book: Why You Are the Way You Are”.

Moore, G.A., Cohn, J.F., & Campbell, S.B. 1997. Mothers’ affective behavior with infant siblings: Stability and change. Developmental Psychology.

Paulhus, D. L., Trapnell, P. D., & Chen, D. (1999). Birth-order effects on personality and achievement within families. Psychological Science.

Price, Joseph (2008). “Parent-Child Quality Time: Does Birth Order Matter?”

Skalkidou, A. 2000. “Parental Family Variables and Likelihood of Divorce”.

Sulloway, F. J. (1995). Birth-order and evolutionary psychology: a meta-analytic overview. Psychological Inquiry, 6, 75–80.

Sulloway, F. J. (1996). Born to rebel: Birth-order, family dynamics, and creative lives. New York: Pantheon Books.

Sulloway, F. J. (2001). Birth-order, sibling competition, and human behavior. In H. R. Holcomb, III (Ed.), Conceptual challenges in evolutionary psychology: Innovative research strategies. Dordrecht, the Netherlands: Kluwer Academic.

Toman, W. Family Constellation 1976, New York: Springer.

Zajonc, R. B. (2001). The family dynamics of intellectual development. American Psychologist, 56, 490–496.

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August 8, 2019

Does Birth Order Affect Personality?

Researchers examine the old adage that birth order plays a significant role in shaping who we are

By Corinna Hartmann & Sara Goudarzi

Kristy-Anne Glubish Getty Images

In spite of sharing genes and environments, siblings are often not as similar in nature as one might think. But where do the supposed differences come from? Alfred Adler, a 19th- and early 20th-century Austrian psychotherapist and founder of individual psychology, suspected that birth order leads to differences in siblings.

Adler considered firstborns to be neurotic, because they don’t have to share their parents for years and are essentially dethroned once a sibling comes along. He also considered oldest children dutiful and sometimes conservative. According to Adler, the youngest children are ambitious, while middle children are optimally positioned in the family and are characterized by emotional stability. Adler himself was the second of seven children.

American psychologist Frank J. Sulloway, who, in the mid-1990s, combed history books for leading figures who were firstborns and rebellious ones who were born later, saw a similar trend. Among the later borns, he found lateral thinkers and revolutionaries, such as Charles Darwin, Karl Marx and Mahatma Gandhi. Among firstborns, he discovered leaders such as Joseph Stalin and Benito Mussolini. His explanation? Every child occupies a certain niche within the family and then uses his or her own strategies to master life. Firstborn and single children had less reason to quarrel with the status quo and identify more strongly with the worldview of their fathers and mothers. Younger siblings are less sure of their parents’ view and therefore more often choose alternative paths in life.

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Such categorizations are popular because they’re rather intuitive, and one can always find an example of the sensible big sister or the rebellious young brother in their circle of acquaintances. As such, Adler’s words still appear regularly in educational guides and continue to reverberate in the minds of parents.

Furthermore, some studies confirmed the idea that sibling position can shape personality. For example, a 1968 study showed that, compared with later borns, first borns are less likely to participate in dangerous sports because of fears of physical injury. And a 1980 study of 170 female and 142 male undergraduates showed lower anxiety and higher ego in firstborns, as measured by the Howarth Personality Questionnaire. At times, however, these investigations used questionable methods. For example, members of the same family were often asked to assess themselves in terms of extraversion, openness to experiences, conscientiousness, tolerance and neuroticism. The catch is these surveys were conducted at only one point in time. The older siblings were therefore not only born first but also simply older. It has long been known that adolescents become more conscientious as they age. This trend could account for a large part of the results. Another methodological flaw was that only one person judged his or her own personality and that of his or her siblings. This detail is important because self-perception and the perception of others can sometimes differ considerably. In addition, the test subjects may have subconsciously incorporated the cliché of dutiful older siblings and cosmopolitan later borns into their evaluation and could have thus brought about the expected result themselves.

Meanwhile scientists who analyzed large, transnational data and compared different families with each other have found the effect of sibling succession on personality disappears almost completely. Researchers led by psychologist Julia Rohrer of the University of Leipzig in Germany evaluated data from more than 20,000 interviewees from Germany, the U.K. and the U.S. They compared the personality profiles of siblings but also of people with different birth orders who had never met. The Leipzig psychologists did not discover any systematic differences in personality.

In such studies, researchers must be particularly cautious because, in addition to age, the size of one’s family is another factor that’s intertwined with sibling position. A child from a family of four has a 50 percent chance of being a firstborn; the more siblings, the lower the probability. For example, the fact that many astronauts are firstborns does not necessarily speak to the special qualities of those born first. It’s likely that many astronauts come from smaller families. To better understand these influences, Rohrer and her team controlled forthe number of siblings. That’s because when there are more of them, there are more later borns. So the researchers hypothesized later borns may more often appear in families of lower socioeconomic classes—which could account for differences between children of different-sized families. 

The larger the sample, the more likely even very small effects will be detected. For example, in a 2015 study, which included 377,000 high school students, psychologist Rodica Damian and her colleague Brent W. Roberts, both then at the University of Illinois at Urbana-Champaign discovered that firstborns tended to be more conscientious, extraverted and willing to lead. Contrary to expectations, they were also more tolerant and emotionally stable than adolescents with older siblings. Yet the differences were very small, and the researchers concluded that the importance that is generally attached to sibling position in shaping one’s character is exaggerated.

“It is quite possible that the position in the sibling sequence shapes the personality—but not in every family in the same way,” says Frank Spinath, a psychologist at Saarland University in Germany. “In other words, there may be an influence but not a systematic one. Nevertheless, other influences weigh more heavily when it comes to the differences in character of siblings. In addition to genes, the so-called undivided environment also plays a role. For siblings who grow up in the same family, this includes the respective circle of friends, for example.” Further, parents do not treat their children the same regardless of their birth rank. Studies show that parents react sensitively to the innate temperament of their offspring and adapt their upbringing accordingly.

Damian’s study also found that on average, firstborns enjoy a small IQ advantage over their younger siblings. Those born first also tend to complete their education with a higher degree and opt for traditionally prestigious careers, such as medicine or engineering.

How does this intellectual advantage come about? Adler may be right that the undivided attention given to the first child in early life promotes cognitive abilities. This advantage is already apparent by the age of two. Norwegian researchers Petter Kristensen and Tor Bjerkedal cleverly showed that the difference in intelligence is not linked to biological factors (some had suspected it might be related to physical conditions during pregnancy). They tested children whose older siblings had died early. The researchers’ assumption was that although these children were biologically younger siblings, they assumed the role of the firstborn in the family. Compared with other younger siblings, they achieved better results in intelligence tests.

Does Birth Order Really Determine Personality? Here’s What the Research Says

O ne Friday afternoon at a party, I’m sitting next to a mother of two. Her baby is only a couple of weeks old. They’d taken a long time, she tells me, to come up with a name for their second child. After all, they’d already used their favorite name: it had gone to their first.

On the scale of a human life, it’s small-fry, but as a metaphor I find it significant. I think of the proverbs we have around second times—second choice, second place, second fiddle, eternal second. I think of Buzz Aldrin, always in the shadow of the one who went before him, out there on the moon. I think of my sister and my son: both second children.

I was the first child in our family. I was also fearful of failure, neurotic, a perfectionist, ambitious—undoubtedly to the point of being unbearable. My sister didn’t study as hard and went out more, worked at every trendy bar in town and spent many an afternoon in front of the TV.

I’d long attributed the differences in our characters to the different positions we held in our family. It seemed to me, all things considered, better to be the firstborn: you had to work harder to expand the boundaries your parents set for you, had a greater sense of responsibility, more persistence, and emerged, in the end, more self-confident.

That theory worked in my favor, but during my second pregnancy, I started to feel sorry for my son. Through no fault of his own, he’d missed out on the enviable position of firstborn. It took that sense of pity for me to realize that I could try to uncover the basis of my ideas about the personality traits of first and second children—and whether there was anything to them.

It was 1874, and Francis Galton , an intellectual all-rounder and a half cousin of Charles Darwin, published English Men of Science: Their Nature and Nurture . In his book, he profiled 180 prominent scientists, and in the course of his research Galton noticed something peculiar: among his subjects, firstborns were overrepresented.

Galton’s observation was the first in a long line of scientific and pseudoscientific publications on the birth-order effect. The greater chance of success for firstborns, in Galton’s view, was because of their upbringing, an explanation that fitted in with the mores of the Victorian era: eldest sons had a greater chance of having their education paid for by their parents, parents gave their eldest sons more attention as well as responsibility, and in families of limited financial resources, parents might care just a little bit better for their firstborns.

Read more: I Raised Two CEOs and a Doctor. These Are My Secrets to Parenting Successful Children

The distribution system at the foundation of this is called primogeniture: the right of the eldest son (or less frequently, the eldest daughter) as heir. Among Portuguese nobility in the 15th and 16th centuries, for example, second- and later-born sons were sent to the front as soldiers more often than firstborn sons. Second and subsequent daughters were more likely than eldest daughters to end up in the convent. In Venice in the 16th and 17th centuries, it was generally the eldest brother who was permitted to marry, after which younger brothers would live with him and his family, dependent and subservient.

Apart from a few royal families, primogeniture is no longer the norm in Western countries. Somewhere in the course of the last century, most residents of industrialized countries became convinced that love, attention, time and inheritance should be divided equally and fairly among our offspring.

That’s what my partner and I strive to achieve: equal treatment of our two children. But we can’t get around the fact that first, second and subsequent children have slightly different starting points. The question is what consequences that has, exactly – and how insurmountable they are.

At the start of the 20th century, Alfred Adler, Freud’s erstwhile follower, the one who believed that the arrival of a younger sibling meant the dethronement of the firstborn, introduced the birth-order effect into the domain of personality psychology. According to Adler, the eldest identifies most with the adults in his environment and therefore develops both a greater sense of responsibility and more neuroses. The youngest has the greatest chance of being spoiled and is also, often, more creative. All children in the middle—Adler was a middle child—are emotionally more stable and independent: they’re the peacemakers, used to sharing from the start.

After Galton and Adler, the idea that family position affects personality has been subjected to many a scientific test. These tests generated factoids that undoubtedly still fly across the table at Christmas dinners: that firstborn children are overrepresented as Nobel Prize winners, composers of classical music, and, funnily enough, “prominent psychologists.” Subsequent children, on the other hand, were more likely to have supported the Protestant Reformation and the French Revolution.

There are so many assumptions, there’s so much research, and still there are very few hard conclusions to be drawn.

A friend, the eldest of four, presses into my hands a book that her mother claims to have been all the rage during the 1990s. The title is Brothers and Sisters: The Order of Birth in the Family , and it was written in the mid-20th century by the Viennese pediatrician and anthroposophist Karl König.

What strikes me from the very first pages is the certainty with which König characterizes first, second and third children. For example, he quotes a study that found firstborns to be “more likely to be serious, sensitive,” “conscientious,” and “good” and—this is my favorite—“fond of books.” Later on, these firstborns can become “shy, even fearful,” or they become “self-reliant, independent.” A second child, by contrast, is “placid, easy-going, friendly [and] cheerful”—unless they are “stubborn, rebellious, independent (or apparently so)” and “able to take a lot of punishment.” These typologies most resemble horoscopes, in the sense that it can’t be very hard to recognize yourself – or your children – at least partially in any of them.

By now, studies looking into the birth-order effect number in the thousands. There’s no shortage of popular publications either: titles such as Born to Rebel: Birth Order, Family Dynamics, and Creative Lives and Birth Order Blues: How Parents Can Help Their Children Meet the Challenges of Birth Order have helped spread the idea that your place in the family determines who you are.

In 2003, two U.S. and two Polish psychologists asked hundreds of participants what they knew about birth order. The majority of respondents were convinced that those born earlier had a greater chance of a prestigious career than those born later, and that those different career opportunities had to do with their specific birth-order-related character traits.

In sum, a century after the possible existence of the birth-order effect was first proposed, it had become common knowledge. That knowledge is now so common, in fact, that it lends itself to satire: “Study Shows Eldest Children Are Intolerable Wankers,” a headline on a Dutch satirical news website quipped in 2018.

Read more: I Was Constantly Arguing With My Child. Then I Learned the “TEAM” Method of Calmer Parenting

There is, however, plenty of criticism of birth-order theories and the associated empirical research. It’s not at all straightforward, critics point out, to know what you’re measuring when you try to unravel the factors that shape an individual human life. It’s also very hard to exclude all the “noise,” as physicists in a laboratory would be able to do more easily. This means that traits we might attribute to a person’s birth order may in fact have more to do with, say, socioeconomic status, the size or ethnicity of the family, or the values of a particular culture.

In the early 1990s, a group of political scientists observed with barely concealed exasperation that birth order had been “linked to a truly staggering range of behaviors.” They tried to debunk the myth that even a person’s political preferences were determined by their position in the family by reviewing studies that addressed, among other things, whether firstborns had “an uncommon tendency to enter into political careers,” were more conservative than those born later, and were more likely to hold political office. Their meta-analysis failed to find consistent patterns—but did find myriad methodological flaws.

There are so many assumptions, there’s so much research, and still there are very few hard conclusions to be drawn, although I suppose the latter is often the case, in the social sciences. They tend to provide more nuance rather than painting things in black and white— and rightly so.

Still, I’d like to know if there’s a counterargument to be made, in response to the certainty with which a friend remarks that second children are always “much more chill” than first children. Or to the way a family member takes it for granted that our son, independent and sociable as he is, is a “typical second child.”

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The end of 2015 saw the publication of two studies in which the methodological shortcomings of previous birth-order research (unrepresentative sample sets, incorrect inferences) were largely obviated. In one of these studies, two U.S. psychologists analyzed data about the personality traits and family position of 377,000 secondary-school pupils in the United States. They did find associations between birth order and personality, but besides being so tiny as to be “statistically significant but meaningless,” as one of the researchers formulated it, they also partially ran counter to those predicted by the prevailing theories. For instance, firstborn children in this data set might be a little more cautious, but they were also less neurotic than later-born children.

The other study looked for associations between personality and birth order in data from the United States, Britain and Germany for a total of more than 20,000 people, comparing children from different families as well as siblings from the same family and correcting for factors such as family size and age. Here, the researchers found no relationship between a person’s place in the family and any personality trait whatsoever.

Other recent studies, conducted mostly by economists, do find an association between birth order and IQ: on average, firstborns score slightly higher on IQ-tests – they also tend to get more schooling. This may be due, researchers speculate, to the fact that parents are able to devote more undivided time and attention to their firstborns when they are very small. It’s an effect that has less to do with innate characteristics and more with parental treatment.

For me, it feels as if my children have been given a little extra wiggle room, a more level playing field. Whoever my son is or will become, his personality has not, or in any case not only, been determined by the coincidental fact of his having arrived second. My relief is conditional, of course—science has a tendency to change its mind.

Even so, the authors of one of those 2015 studies cherish little hope of ridding the world of the belief that birth order determines personality. After all, they wrote in an accompanying piece, it takes forever for academic insights to trickle down to the general public. And we tend to be swayed less by scientific results than by our own personal experiences.

My second child is quicker to anger, I once told another mother in a parenting course. But hadn’t my daughter been just as irascible when she was my son’s age?

One of the reasons belief in the birth-order effect is so persistent, they suggest, is because it’s so easily confused with age. Pretty much everyone can see with their own eyes that older children behave differently from younger children. And there’s a good chance that a first child, when compared with a second child, will appear more cautious and anxious. It’s just that this difference probably has more to do with age than with birth order.

My second child is quicker to anger, I once told another mother in a parenting course. But hadn’t my daughter been just as irascible when she was my son’s age? I’d described my son, who was almost 2 years old at the time, as more emotionally stable. Perhaps what I’d meant is that I can easily discern his emotions: they’re still so close to the surface. He sulks when something doesn’t go his way, bows his head and looks askance when he’s doing something he knows he shouldn’t, throws everything within reach on the floor when he’s angry. When he’s excited, he wags—it doesn’t matter that he lacks a tail. His sister’s feelings have already grown more subtle and complex, and the way they’re expressed has become hard to read, for her own 5-year old self as well as for me.

That difference in age might also be the reason that children from the same family are often assigned specific roles, a Dutch developmental psychologist tells me when I present her with the hypothesis of the two U.S. researchers. That way, even if there are no fixed differences in personality , we might still impose differences in behavior . Parents tell the eldest to be responsible, and the youngest to listen to the eldest. The behavior that follows from this is an expression of that role, not of a person’s character.

I think of the way we tried to prepare my daughter for the arrival of her little brother. How we told her that soon there would be someone who couldn’t do anything at all. She’d be able to explain everything to him, we’d said, because she already knew so much. The prospect had appealed to her. Little did we know we were talking her into a stereotype-perpetuating role.

Of course, all the circumstances in which a child comes into the world—whether they’re born male or female, in war or peace, into relative poverty or exorbitant wealth—end up making a person who they are. But the birth-order effect seems to particularly enthuse and preoccupy us.

Perhaps because it’s so concrete: it’s rather more fun and more satisfying to attribute a baby’s generous smile to the fact that he’s a second child than to a vague interplay of personality and environment, expectations and discernment.

And perhaps that’s also what makes it so tempting to attribute the effect to ourselves. It absolves us for a moment of the responsibility for who we are and the duty to turn ourselves into who we want to become: my being neurotic isn’t my fault, it’s just because I’m the eldest.

My son began to dole out little smiles when he was barely 4 weeks old. They were not just twitches or reflexes, I knew for sure, but outright attempts at contact. He began smiling earlier than his sister had, and this made sense to me: he was the second child, and so the more sociable one, just like my own sister.

It didn’t occur to me in that moment that my interpretation of his smile was founded on stories we’d been passing on for generations. It’s only now that I’m beginning to understand that those stories have a history. And that, without us really realizing it, they might shape our children’s present as well as their future.

Excerpted from Second Thoughts: On Having and Being a Second Child by Lynn Berger. Published by Henry Holt and Company, April 20th 2021. Copyright © 2020 by Lynn Berger English translation copyright © 2020 Anna Asbury. All rights reserved.

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Home — Essay Samples — Psychology — Developmental Psychology — Birth Order

Essays on Birth Order

Birth order and its impact on personality and development have intrigued psychologists, educators, and scholars for decades. The concept suggests that the order in which a child is born within a family can significantly influence their character, career, and relationships. As a complex and fascinating topic, it provides a rich basis for academic exploration and essay writing. This guide aims to delve into the nuances of birth order, offering insights and strategies for students crafting their essays on this subject.

The Essence of Birth Order Essays

Birth order essays explore the theory that an individual's personality traits, behaviors, and life choices can be influenced by their position among siblings in the family unit. These essays often analyze the roles of first-borns, middle children, last-borns, and only children, drawing on psychological theories and empirical research to support their discussions. A well-crafted birth order essay not only presents arguments and evidence but also critically examines the counterarguments and limitations of birth order theories.

Topics to Explore in Birth Order Essays

• Personality Traits and Birth Order: Discuss how first-borns often assume leadership roles, middle children develop negotiation skills, and last-borns might exhibit more rebellious traits.
• The Influence of Birth Order on Career Choices: Explore the tendency for first-borns to choose careers in law, medicine, or engineering, while later-borns may gravitate towards creative or entrepreneurial paths.
• Birth Order and Family Dynamics: Analyze how birth order affects sibling relationships, parental expectations, and family roles.
• Comparative Studies Across Cultures: Examine how cultural differences impact the effects of birth order on personality and behavior.

Advantages of Using Birth Order Essay Samples

Utilizing essay samples as references can significantly benefit students in several ways:

• Structural Guidance: Samples provide a blueprint for organizing an essay effectively, from the introduction and thesis statement to the body paragraphs and conclusion.
• Ideas and Inspiration: Reviewing various samples can spark new ideas and perspectives, enriching the essay's content and approach.
• Understanding of Academic Standards: Samples illustrate how to properly cite sources, integrate evidence, and maintain academic integrity.
• Critical Thinking: Analyzing different viewpoints within samples enhances critical thinking and analytical skills, encouraging a balanced and well-argued essay.

Strategies for Writing an Impactful Birth Order Essay

• Choose a Unique Angle: While many essays have been written on birth order, finding a unique angle or focusing on a less-explored aspect can make your essay stand out.
• Incorporate Current Research: Including recent studies or findings adds depth and relevance to your essay, demonstrating engagement with ongoing scholarly discussions.
• Balance Personal Insight with Scholarly Evidence: While personal observations can enrich an essay, it's crucial to support arguments with empirical evidence and scholarly research.
• Reflect on Implications: Discuss the broader implications of birth order theories on education, counseling, parenting strategies, and societal norms.

The Role of Birth Order in Shaping Individuals

Birth order is more than just a theory; it's a lens through which we can understand the complexities of human behavior and personality development. Writing an essay on this topic offers a unique opportunity to explore how familial positions influence individuals in multifaceted ways. By leveraging essay samples, focusing on insightful research, and engaging critically with the material, students can produce compelling essays that contribute meaningfully to the discourse on birth order.

Whether you're an aspiring psychologist, an educator, or simply curious about the dynamics of family life, essays on birth order provide a platform to explore the intersections of psychology, sociology, and personal experience. As you embark on this academic journey, remember that the key to a successful essay lies in thorough research, critical analysis, and a deep understanding of the nuances of birth order theory.

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Does being the oldest or youngest sibling really shape your personality?

The psychological debate about sibling order has persisted for decades—but it might be time to break up with the popular theory.

Are you a responsible oldest child, an overlooked middle, or a free-wheeling baby? For those who adhere to the theory that birth order influences personality, the answer to that question may hold the key to who you are as a person. At parties, family dinners, and therapy sessions, people can use birth order as a kind of shorthand for personality traits—an only child’s selfishness, perhaps, or a middle child’s struggle for visibility.

But though your personal experiences may very well indicate that birth order forms the personalities around you, psychologists beg to differ. Here’s why it might be time to drop the stereotypes.

Origins of the psychological theory of birth order

The idea that birth order influences a child’s personality might be as old as people themselves. After all, various societies have long privileged—or overlooked—people based on where they stand in their family.

In many ancient societies, for example, the arrival of a first child—and thus a parent’s transition to the head of a family—often translated to a higher social status. It also gave rise to ceremonies like special baths for first-time mothers in Micronesia and the traditional pidyon haben   ceremony in Judaism, during which a first-born son is “redeemed” by paying five silver coins to a priest.

( Siblings can have surprisingly different DNA ancestry. Here's why .)

Birth order has also long determined inheritance rights and royal lines of succession, as in the British monarchy which has long demanded a first-born “heir” and one or more “spares” as backups should something happen to the heir.

But the psychological theory of birth order didn’t develop until the early 20th century, when psychologist Alfred Adler theorized that birth order influenced not just social status, but a child’s development and personality. Known as the father of individual psychology, Adler theorized that an individual’s “family constellation” results in predictable personality traits. “The position in the family leaves an indelible stamp upon the individual’s life style,” Adler wrote in 1931.

According to Adler, the birth of a sibling deprives oldest children of their parents’ undivided attention—and as a result they are neurotic, more prone to conservatism, and inclined to imitate their elders. Second children are competitive attention-grabbers, while youngest children are pampered and lazy. Finally, he theorized that people who grow up without siblings have a “mother complex” and are in rivalry with their father.

Famous for his international lectures, popular psychology texts, and psychotherapeutic techniques, Adler’s influence still resounds throughout the field of psychology—and as a result, generations of psychologists undertook research that attempted to prove his theory of birth order.

What the research actually says about birth order

Studies conducted since Adler’s time have found associations between birth order and everything from educational attainment to sexuality to middle children’s success in team sports.

Frank Sulloway, one of the theory’s most prominent modern advocates, looked at adults and their careers in the 1990s and 2000s to assess the influence of birth order. He found a tendency for conservative research among famous firstborn scientists, with more radical research, such as the theory of evolution and relativity, more common among famous scientists born later in their family order. He also found differences between military and political strategies among militant firstborns like Maximilien Robespierre and moderate, nonviolent methods among famous middle-borns.

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But the studies that most applicable to personality development look at the “big five” personality traits of openness, conscientiousness, extroversion, agreeableness, and neuroticism. And more recent birth order studies throw cold water on the theory that your birth order can shape your personality.

( Not an extrovert or an introvert? There's a word for that .)

Rodica Damian, an associate professor of psychology at the University of Houston, conducted one of the largest such studies in 2015, using data from a longitudinal study of over 440,000 U.S. high school students. After controlling for socioeconomic status, sex, and age, the study showed that “the association between birth order and personality traits is as close to zero as you can get,” she says.

Another 2015 study underscored Damian’s findings: After analyzing three nationally representative samples from the U.S., Great Britain, and Germany, researchers wrote “we consistently found no birth-order effects on extraversion, emotional stability, agreeableness, conscientiousness, or imagination.”

But both teams of researchers found evidence for one trait that would please firstborn children (and dismay their younger siblings): The studies each showed that firstborns were slightly more likely to have high verbal intelligence.

This doesn’t necessarily mean that firstborns are smarter or learn more easily, Damian says. More likely it’s because firstborns spend more time around adults in their early childhood—and she points out that in her study, the difference was a matter of a single IQ point.

Overall, the other study team wrote, “we must conclude that birth order does not have a lasting effect on broad personality traits outside of the intellectual domain.”

What really makes a personality?

As a scientist, Damian is cautious about claiming that any theory has been “disproven.” However, she says that modern research essentially debunks the theory that birth order affects personality—which she calls a “zombie theory” because it just won’t die. So why does the idea still enchant the public—and why do researchers continue to plumb the question?


“Everybody has an opinion on it because everybody has a birth order, even only children,” says Damian. And part of the reason we just can’t quit birth order psychology may have to do with our own experiences that will always appear to support it. Older children will always seem to be more responsible and sophisticated than their younger siblings because they are more developmentally mature.

( How much does your name influence your future? It might surprise you .)

“Even though you see this and it's true, you don't have a magic lens to go back in time and observe the children at the [exact] same age,” Damian explains. It’s a “perfect confound,” she and her colleagues write—and it’s “one circumstance where personal experience will be wrong and the truth can only be discovered through good scientific reasoning and investigation.”

In truth, the science of personality development is anything but settled. Modern research using twin studies suggests that personality formation is about 40 percent due to genetics. The rest may be a matter of a complex combination of environment and cultural practices that help shape the disposition with which we’re born.

Though researchers can measure the “big five” personality traits, it’s harder to quantify the subjective experiences that shape our everyday lives and, perhaps, our personalities. Damian is currently studying the possible effects of people’s life narratives —the stories they tell themselves about their own experiences—on the people they become. But for much of the public, teasing out the complex web of nature and nurture is far less fun than teasing our siblings.

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Birth Order Theory: Insights Into Your Personality

Personality can develop from various sources and influences in a child's life, including birth order. Studying personality and its formation has interested researchers, psychologists, and scientists for centuries. Enduring characteristics, traits, and behavior can shape each person's unique adjustment to life.

Birth order theory suggests that while personality is mainly unpredictable, specific general characteristics can be linked to a person's birth order in their family. Birth order refers to the rank of siblings in relation to age. It's thought that parents intentionally or unintentionally assign roles based on birth order, which may impact a child’s personality development.

In this article, we'll explore the theories and studies behind personality development, focusing on birth order theory.

Birth order theory: Why it matters

Theories on personality formation, adaptation, and environmental influences across cultures vary. The concept of birth order is often credited to Austrian psychoanalyst Alfred Adler in the early 1900s. He was one of the first to explore the idea that a person's place in their family tree could predict personality traits. 

Adler believed that firstborn children typically have higher expectations placed upon them by parents and thus develop a greater sense of responsibility and ambition. He proposed that later-born siblings, on the other hand, were often treated more leniently by their parents compared to firstborns, leading them to become more rebellious and independent.

However, it is important to note that Adler's theories are not universally accepted, and a person's place in their family tree does not always dictate their personality traits. Ultimately, each person is unique and should be treated as such. Each person has strengths and weaknesses independent of their birth order.

What birth order theory is not

Birth-order personality traits are not necessarily present when a child is born into a family. For example, firstborn children are not necessarily born with niche or particular personality traits ingrained in their psyche. Instead, in birth order theory, Adler illustrates how family environments and dynamics can shape individual psychology during a child's formative years. Although every family is different, there are similarities in the interactions between parents and children and siblings.

The family's role in birth order personality traits

Birth order research and studies show several influences shaping personality in addition to birth order. Common factors include:

• Biological: Children tend to inherit many traits and features from their parents. These can include intelligence, courage, and physical characteristics.
• Social: By interacting with others in an individual's social circle, children learn behaviors and thought patterns from their experiences, like those in the education system and beyond.
• Cultural: A child growing up within a culture consciously or unconsciously can adopt traits consistent with the culture's beliefs, ideas, and norms.
• Physical Environment: An individual's surroundings often impact the development of personality. For example, the personalities of those growing up in a rural area may differ from those living in an urban environment.
• Situational: As a child grows up, they face different situations, which may help them adapt and change their personality. These situations could include meeting new friends, experiencing trauma, or welcoming a new sibling.

When looking at these factors, we see family life can incorporate all of these. Since most children's lives are, at first, shaped by everything going on in the family, it makes sense that some psychologists have remained interested in birth order theory throughout the years since Adler first proposed his idea.

How birth order may affect personality

The following traits are general examples of how birth order differences and personality may be related. Of course, many other factors could impact the development of a child's personality; some of these reasons will be discussed further below.

These children tend to get much more attention from adults than a child with siblings does. This means many of their early interactions involve individuals significantly older than them. These interactions can make them feel like "tiny adults," and they can seem more mature than their peers with siblings. Traits may include:

• Maturity for their age
• Sensitivity
• Use of adult language
• Self-centeredness
• A tendency to enjoy being the center of attention
• Refusal to cooperate with others
• A tendency to feel unfairly treated when not getting their way
• A desire to be more like adults, so may not relate well with peers

First child

Since the firstborn child is used to being an only child until siblings come along, they may exhibit some of the characteristics of an only child. Also, the firstborn may have these birth order personality traits:

• Achiever and leader
• Feelings of superiority over other children
• Difficulty when the second child is born, such as feeling unloved or neglected
• A tendency to be controlling and focused on being correct about results
• Use of good (or bad) behavior to regain parents' attention
• A tendency to be bossy or authoritarian about rules
• A desire to please others
• Reliability

Second child

Second-born and middle children begin their lives with their parents' attention on the firstborn. Having an older sibling as a role model makes second-born and middle children try to catch up with older children. Adler believes the second child can be better adjusted. A second child may:

• Be more competitive
• Lack of the undivided attention of parents
• Be a people pleaser
• Be a peacemaker
• Develop abilities the first child doesn't exhibit to gain attention
• Be rebellious
• Be independent and not need the support of others

Middle child

Many have heard of the "middle child syndrome" and the difficulties these children can present. They may become frustrated or resentful of the significant changes they experience early in life. Not only do they lose their "youngest child" status, but they also must compete for attention with older and later-born children. 

Middle-born children in larger families are typically less competitive than single middle children. Their parents' attention can be spread thinner due to the dynamics of a bigger family. Middle children in bigger families may be more prone to use cooperation to get what they want. Middle children may demonstrate the following tendencies:

• Can feel life is unfair
• Can be even-tempered
• May feel unloved or left out
• May not have the rights and responsibilities of the oldest sibling or the privileges of the youngest
• May be adaptable
• Can be impatient
• May be outgoing and rambunctious
• May treat younger siblings more roughly
• Can feel "squeezed" in the family environment

Youngest child

The "baby" of the family tends to get more attention from parents since the older siblings are developing and becoming more independent. Traits of the youngest child may include the following:

• May be charming and outgoing
• Can be an attention seeker
• Behaves like the only child
• Feels inferior, like everyone is bigger or more capable
• Expects others to make decisions and take responsibility
• May not be taken seriously
• Can become "speedier" in development to catch up to other siblings

Other factors that may influence birth order personality

Each family is different and has unique dynamics. The subject of birth order positions alone will not determine the complexities of a person’s personality. Certain circumstances or measures may impact a child's personality as children and families develop and evolve. Across different families, children of the same birth order can show diverse personality differences, especially across a large representative sample.

Blended or step-families

When two parents remarry, especially when children are in their formative years, the family of origin often goes through a period of disorientation and competition. For example, two firstborns in the new family may search for their "place" and may compete to keep their "firstborn status."

Differences in ages

When there is an age gap of three or more years between siblings, it is common for the birth orders to restart. In a family with many children, this could create birth order subgroups with varying birth order effects.

Health and mental issues

A child born with significant physical or neurodevelopmental disabilities can seem to remain in the "youngest" position regardless of birth order. It may impact the psychological birth order position of the other children.

Gender of siblings

Most psychological competition tends to occur between children of the same gender and similar ages. The competition, partly for parental attention , can start in childhood and move into young adulthood and beyond.

Death of a sibling

The impact of a child's death can be devastating for families. Some children may adapt by developing overindulgent tendencies. Also, a glorification of the deceased child can occur, whereby other siblings may never live up to the image of the deceased sibling. It can profoundly alter the birth order effect.

An adopted child often has special circumstances in the family dynamic. Having an adopted child may be seen as a special gift for parents with difficulties conceiving. These parents may have a greater tendency to spoil or overindulge the child. When an adopted child comes into an established family, they may find difficulties fitting into the dynamic.

Does a correlation between birth order and personality exist?

Multiple factors, including socioeconomic status, parental attitudes, gender roles, and social influences, can also shape an individual's personality. In a study of more than 20,000 participants, however, details revealed no significant effects of birth order of the Big Five personality traits: extraversion, emotional stability, agreeableness, conscientiousness, and openness to experience.

However, some research has linked higher intelligence to a family's older children. It could be because parents have more emotional and intellectual resources to give when fewer children are present in the home.

Gain additional insights into your personality in therapy

If you’d like to gain more insight into your personality or how your birth order shapes it, consider working with a mental health professional. With a therapist, you can explore how your early childhood experiences shape your current behavior and develop coping skills to help you navigate life’s challenges. Your therapist can also provide evidence-based strategies for managing challenging emotions and building healthy relationships.

If you are not interested in traditional in-person therapy, consider using online counseling through BetterHelp . Online therapy can be a convenient way to get mental health care. Research suggests that online treatment is  as effective as in-person therapy and can often fit into your schedule more easily. You can speak with a therapist from your home or anywhere you have internet connection.

How does birth order affect the development of our personality?

According to Alfred Adler’s psychological theories, birth order affects personality development through its impacts on relationship dynamics, including both sibling relationships and parent-child interactions. Since a person’s family is almost always their first experience of connections with other people, it may shape the assumptions, habits, and strategies that individuals carry throughout their lives. 

For example, Adler believed that eldest children were more prone to neuroticism. He thought that their experience of undivided parental attention in their early years, followed by the appearance of younger siblings who competed for attention, could lead to a sense of insecurity. On the other hand, he also believed firstborn children tended to form leadership skills early on due to the experience of teaching and protecting younger siblings. 

There might also be biological effects of birth order. Some researchers have suggested that changes to a woman’s immune system following repeated births might have developmental impacts on the personalities of children born later. However, the evidence for this theory is currently very limited, and some research seems to contradict it .

In twins, birth order might appear to affect personality because the larger and healthier twin is often born first . This can mean that younger twins are more likely to have health and developmental problems, which may have long-term psychological impacts. 

How does birth order affect socialization?

Birth order might affect socialization because of the different roles that siblings of different ages tend to assume within a family. The oldest child might feel a sense of responsibility for their younger siblings, causing them to develop a greater propensity for leadership. Youngest children, in contrast, might have to struggle for their independence when their older siblings get bossy. This could lead them to be more rebellious in later interactions. Middle children might find themselves taking on the role of mediators, causing them to develop strong interpersonal skills.

Is birth order an important factor in determining intelligence myth?

Some studies have found a possible birth order effect on intellectual achievement. A 2015 research paper reported that older children appeared to score slightly higher on measures of intelligence, as well as rating their own intelligence higher. Later borns tended to display slightly lower IQ along with lower intellectual confidence.

However, while the observed effect was statistically significant, it was quite small. There’s little evidence that birth order plays a major role in determining a person’s intelligence.

What are three arguments made to support that birth order does affect our personalities?

One common argument in favor of the idea that birth order can shape personality is that early childhood experiences are known to be important for many different long-term psychological outcomes, such as relationship attachment styles. Since the experiences of siblings may be different depending on their position in the family, it might make sense to expect them to be important in personality formation.

Another argument in favor of birth order effects is that parental attention may be important in forming cognitive abilities. Because children with fewer siblings receive more of their parents’ focus, they might have a slight advantage in building certain mental skills, which could in turn affect their personalities. 

The third main argument supporting birth order personality effects is that this idea is backed by research. Although the birth order effects found so far have been small, many important shifts in scientific theories begin with the observation of seemingly minor phenomena.

Does birth order affect one's personality impression?

There’s currently not much evidence that birth order affects the kinds of personality traits that are most important in determining the impression an individual makes on others. Even in the study offering the strongest support for the effect of birth order on intelligence, researchers found no relationship between birth order and characteristics such as:

• Agreeableness
• Willingness to try new experiences
• Extraversion
• Emotional stability
• Imagination
• Conscientiousness

How can birth order impact a child's attitude and behavior?

Birth order might affect a child’s behavior through the differences in parental expectations for different family members. Parents may consciously or unconsciously assign older siblings to a leadership role, expecting them to care for and instruct their younger brothers or sisters. Younger children might receive less discipline because their parents are older or have less ability to monitor an individual’s behavior within a large family.

Predicting the exact outcomes of these kinds of expectations may be difficult, though. An eldest child expected to act as a teacher and protector for their siblings might embrace this role. However, if they’re given poor support from their parents or punished for their siblings’ misbehavior, it could lead to resentment and avoidance of responsibility.

Birth order might also play a role in determining mental health, which could have important behavioral effects. A 2021 study reported that later-born children appeared to have lower rates of mental disorders and higher rates of happiness and prosocial attitudes.

Some theories of birth order suggest that “psychological birth order” might matter more than actual birth order. In other words, a child’s perception of their place within the family might be the most important factor.  It’s often said that if a child is born five years or more after their next-oldest sibling, their personality characteristics will be more similar to a firstborn.

Can birth order determine success or failure?

Despite the prevalence of stories in popular media about how many astronauts or Nobel Prize winners are firstborn children, birth order is unlikely to be a major factor in a person’s success or failure in life. 

While many psychologists used to consider it very important, more recent studies with better methodological design have found little evidence for strong effects. Other elements, such as genetics, socioeconomic standing, developmental health, and life experiences, are likely to be substantially more important.

Does birth order seem like a good way to describe personality?

Many people use birth order as a shorthand for personality makeup, such as describing someone as a “typical middle child”. Yet many people have very different ideas about what this means in practice. For instance, some sources may describe oldest children as outgoing and independent, while others say that these people tend to be shy and cautious. 

Because of these differences, and the lack of strong evidence in favor of birth order effects, these stereotypes may not be useful ways to describe someone’s personality.

Does birth order affect self-concept?

Some theories of birth order effects have suggested that a person’s family position might affect their self-concept. In these frameworks, older and only children were thought to have the highest self-esteem, while middle children were believed to have the lowest. Several studies in the 1980s and 1990s tested these theories in middle and high school students with mixed results. While some researchers reported significant birth order effects, others found that the evidence was weak and inconsistent. 

More recent investigations have found little support for the idea that self-esteem is affected by birth order. There may not be enough evidence to definitively state that oldest, middle, and youngest children have different self-concept strengths.

Does birth order affect the behavior of children?

Birth order may have some effects on childhood behavior. Research on children aged 9-10 found the highest rates of cooperative, prosocial behavior among those who were latest in birth order. Eldest children seemed to be more prone to conduct problems and disruptive behavior. That said, these findings may need to be replicated before it’s possible to say definitively that birth order impacts behavior.

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What to Know About Birth Order

Birth order has been used to predict success, prosperity, jobs, and more. But does it really affect who you are and what you do in life? Here's a closer look at the truth and science behind birth order.

The Science of Birth Order

A researcher named Alfred Adler developed birth order theory in the 20th century. The theory claims that the order in which a child is born shapes their development and personality. Adler also claimed that family, community, and social aspects play a major role in shaping a child’s personality.

Today, many psychologists believe that where you fall in your family’s birth order has a major impact on your personality development.

Oldest child. If you're the firstborn child, you have your parents all to yourself for a period of time. Because it’s your parents’ first time being parents, they tend to dole out attention to you. They’re also extra careful when it comes to all aspects of child rearing — from bumps and bruises to early education. Eldest children benefit from all this attention. 

Your parents might expect a lot from you if you're the oldest, especially as other children are born into your family. Your parents might seem stricter with you, and often expect you to set an example for your younger siblings and show responsibility.

Studies show if you're the eldest child, you tend to demonstrate leadership skills. Maybe you're a leader in the workplace already, or rising to the top of your industry.‌

Middle child. It’s a stereotype that if you're a middle child you're a peacekeeper, but there seems to be a grain of truth behind the saying. Because you lack the title of being the oldest or the youngest, you seek to carve out a niche for yourself in the family dynamic . You tend to enjoy negotiation and compromise. You can often relate to people of different ages with ease.

You can be competitive with your older sibling — maybe by breaking their sports records, becoming more fluent in a language, or getting better grades. Or you might behave more rebelliously.

Youngest child. As the baby of the family, you tend to take one of two paths when developing your personality, according to Adler. The first path is a clear journey to success, where you try to excel in every way, often becoming the go-to person in the family. Youngest children can also become avoidant if they lack the confidence or drive to excel.

You might have freedoms your older siblings don't have. As your parents’ rules become more relaxed, your parents can be more hands-off with you. You're usually assured of your place in the family and can be very creative, rebellious, and outgoing.

Only child. If you're an only child, you've been surrounded by adults since birth. That’s not to say you weren’t socialized with other children through kindergarten, the playground, or school. But during your time at home you socialized with parents and other adults, mimicking their behaviors and becoming "small people".

Your parents might be overprotective of you, leading you to become dependent on your parents for support. You aren’t used to sharing clothes, space, or parental attention with siblings. This can make you intelligent and creative, but also stubborn and set in your ways.

Birth Order and Intelligence

Some theories claim that firstborns are more intelligent and have a higher IQ than later-borns. But the most recent studies show that firstborns only hold a 1-point IQ advantage on average over their siblings. Social factors could be to blame for this idea. 

Another study shows that firstborns might benefit from being surrounded by adults during their first years. They absorb the way adults talk, while later-borns are more exposed to the less-developed ways their siblings speak. 

The same study found that firstborns often take a leadership and teaching role to their younger siblings. Some theories say tutoring improves the intelligence of the tutor — in this case, the older sibling. 

Birth Order and Health

Some people think birth order affects health. Studies suggest if you’re the oldest, you're more likely to have a lower birth weight than your siblings. 

Later-born children have an increased risk of hospitalization due to avoidable accidents. This could relate to a lack of parental attention in a large family. Younger siblings may struggle with mental health during puberty and young adulthood, and are more likely to be admitted to the hospital for reasons relating to alcohol. 

Overall, researchers found most birth order differences are due to where your parents choose to spend their time and resources. 

Other Factors That Influence Birth Order

Birth order is a complex subject. There isn’t a “one-size-fits-all” for every family. Different factors affect social family dynamics, and results differ from child to child and family to family.

Some other factors that influence birth order include:

• Parental attitudes and culture. In some cultures, even if a boy is born after four girls, he may still be treated as the oldest.
• Age difference. Adler notes that if children have an age difference of more than three years, subgroups with different dynamics may form. Most experts agree, but place the age gap at five years.
• Twins. Most twins get special attention from parents, so experts say these rules don’t necessarily apply.
• Confidence. A child’s opinion of themselves determines their outlook and attitude. While birth order helps shape their personality, it’s not the only factor.

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Birth Order Theory: How Sibling Rank Influences Personality and Behavior

The formation of human personality has long been a captivating subject of study for researchers, psychologists, and scientists. Among the various theories and influences that shape an individual's unique traits and behaviors, one that has garnered significant attention is the concept of birth order. The notion that the order in which a child is born into a family can profoundly impact their personality development has intrigued scholars and the general public alike.

Let's delve into the intriguing realm of birth order theory , exploring its origins, key insights, and the ongoing scientific debate surrounding its validity. We'll examine how a person's position within the family hierarchy - whether they are the eldest, a middle child, the youngest, or an only child - can potentially shape their psychological makeup, interpersonal dynamics, and life trajectories. By synthesizing the latest research and real-world anecdotes, we aim to provide you with a nuanced understanding of this captivating field of study and its implications for your own self-discovery.

The Birth Order Theory: A Historical Perspective

The foundations of birth order theory can be traced back to the early 20th century, when the renowned Austrian psychotherapist Alfred Adler introduced the concept of the "family constellation." Adler, who was heavily influenced by the pioneering work of Sigmund Freud, proposed that a child's place within the sibling hierarchy profoundly shapes their personality, strengths, and weaknesses.

Adler's groundbreaking ideas centered on the notion that each child's "psychic situation" is unique, shaped by the order in which they arrive into the family. He believed that parents, consciously or unconsciously, assign distinct roles and expectations to their children based on birth order, which in turn can impact the child's psychological development and subsequent behavior.

The Firstborn: A Sense of Responsibility and Achievement

According to Adler's theories, firstborn children often find themselves in a unique position. As the initial recipients of their parents' undivided attention and affection, these children may develop a heightened sense of responsibility and a strong drive to excel. Adler proposed that firstborns are more likely to exhibit traits such as:

Heightened ambition and a desire to achieve

A tendency to be dutiful, perfectionistic, and conventional

A greater sense of responsibility, often taking on a leadership role within the family

A more serious and cautious approach to life

A strong desire to please their parents and uphold family traditions

Adler's research suggested that the arrival of younger siblings can sometimes trigger feelings of insecurity or resentment in firstborns, as they navigate the shift from being the sole focus of parental attention. This, in turn, may contribute to the development of neurotic tendencies or a need for control in some firstborn individuals.

The Middle Child: Navigating the Balancing Act

Adler's birth order theory also sheds light on the unique challenges and potential strengths of middle children. As the "sandwich" between the firstborn and the youngest, these individuals may often feel overlooked or neglected, leading to a perceived lack of emotional and financial support from their parents.

Adler proposed that middle children may develop the following characteristics:

A heightened sense of independence and the ability to form strong bonds outside the family

A tendency to be more adaptable and cooperative, as they learn to navigate the dynamics between older and younger siblings

A potential struggle with low self-esteem or a sense of being "lost in the middle"

A drive to differentiate themselves from their siblings and find their own unique niche

A propensity for becoming the "peacemaker" within the family

Interestingly, Adler noted that the specific traits of middle children may be influenced by factors such as the age gap between siblings and the gender composition of the family. For instance, a middle child who is the only male or female sibling may exhibit a different set of personality traits compared to a middle child with same-sex siblings.

The Youngest Child: Charming, Outgoing, and Competitive

Adler's birth order theory also sheds light on the potential characteristics of the youngest child. As the "baby" of the family, these individuals may receive more attention and indulgence from their parents, which can shape their personality in unique ways.

Adler believed that youngest children often develop the following traits:

A charming, outgoing, and attention-seeking demeanor

A tendency to behave in a more carefree and playful manner, akin to an "only child"

A sense of feeling inferior or disadvantaged compared to their older, more capable siblings

A drive to "catch up" to their siblings, leading to a competitive spirit

A reliance on others to make decisions and take responsibility

Adler suggested that the youngest child's attempt to differentiate themselves and gain attention within the family dynamic can contribute to the development of these distinct personality characteristics.

The Only Child: A Unique Position

While not technically a birth order position, the experience of being an only child has also been the subject of Adler's theories and subsequent research. Adler believed that only children occupy a unique psychological space, as they do not have to share their parents' attention and resources with siblings.

Adler proposed that only children may exhibit the following traits:

A heightened sense of maturity and responsibility, as they often interact with adults more than their peers

A tendency to be creative and intellectually curious, potentially due to the undivided attention and resources provided by their parents

A potential struggle with independence and self-reliance, as they may be more accustomed to being the sole focus of their parents' care and support

A desire to please their parents and uphold family traditions, as they may feel a greater sense of responsibility to fulfill their parents' expectations

Interestingly, research has suggested that only children may be more likely to achieve academic and professional success, potentially due to the increased resources and support they receive from their parents.

Beyond Birth Order: Factors That Shape Personality

While birth order theory offers a compelling framework for understanding personality development, it is important to recognize that an individual's psychological makeup is shaped by a complex interplay of various factors. These include, but are not limited to:

Genetics and Biological Factors: An individual's innate traits, such as intelligence, temperament, and physical characteristics, can have a significant impact on their personality.

Socioeconomic Status: The family's socioeconomic background, including factors like income, education, and access to resources, can influence a child's upbringing and, in turn, their personality.

Parenting Styles and Family Dynamics: The way parents interact with and raise their children, as well as the overall family environment, can profoundly shape a child's psychological development.

Peer Relationships and Social Influences: An individual's experiences and relationships outside the family, such as with friends, teachers, and social groups, can also contribute to their personality formation.

Significant Life Events: Traumatic experiences, major life transitions, or other significant occurrences can also have a lasting impact on an individual's personality and behavior.

It is important to acknowledge that while birth order may play a role in shaping an individual's personality, it is not the sole determinant. A person's unique combination of genetic, environmental, and experiential factors ultimately contributes to the development of their distinct psychological profile.

The Ongoing Debate: Empirical Evidence and Skepticism

As with many psychological theories, the validity and strength of birth order theory have been the subject of ongoing debate and research. While some studies have found support for the influence of birth order on personality traits and cognitive abilities, other researchers have questioned the robustness of these findings.

A 2015 study by psychologist Rodica Damian, for example, found a small but statistically significant link between birth order and intelligence, with firstborn children displaying a slight advantage in IQ scores. However, the same study also noted that the effect size was quite modest, suggesting that birth order alone does not have a substantial impact on intellectual abilities.

Similarly, a comprehensive review published in 2018 examined the relationship between birth order and the "Big Five" personality traits (extraversion, emotional stability, agreeableness, conscientiousness, and openness to experience). The researchers concluded that while some birth order effects were observed, they were generally small and inconsistent across different studies.

This lack of robust, consistently replicated findings has led some psychologists to question the strength and practical significance of birth order theory. Critics argue that other factors, such as socioeconomic status, parenting styles, and individual differences, may play a more influential role in shaping personality than birth order alone.

Navigating the Complexities of Birth Order

Despite the ongoing debate, the concept of birth order theory continues to captivate the public's imagination, with numerous anecdotal accounts and personal experiences lending support to the idea that birth order can shape an individual's personality and life trajectory.

One such example is the TikTok trend surrounding the "birth order dating theory," which explores how an individual's birth order may influence their romantic relationships and compatibility with partners of different birth orders. While the scientific evidence for these specific claims remains limited, the popularity of such discussions highlights the widespread interest in understanding the potential impact of birth order on human behavior and relationships.

As with any psychological theory, it is important to approach birth order with a nuanced and balanced perspective. While it may offer valuable insights into an individual's personality and interpersonal dynamics, it should not be viewed as a definitive or deterministic predictor of behavior. Each person is unique, and their psychological makeup is shaped by a complex interplay of factors that extend far beyond their position within the family hierarchy.

Embracing Your Birth Order: Strategies for Self-Discovery

If you are intrigued by the concept of birth order theory and its potential relevance to your own life, there are several strategies you can employ to explore its implications further:

Reflect on Your Own Experiences: Consider how your birth order position may have influenced your personality, relationships, and life choices. Are there any patterns or tendencies that resonate with the characteristics associated with your birth order?

Observe Family Dynamics: Analyze the interactions and roles within your family, paying attention to how birth order may have shaped the way your parents and siblings perceive and treat one another.

Seek Professional Guidance: Consult with a licensed mental health professional, such as a therapist or psychologist, who can provide a more comprehensive and nuanced understanding of how your birth order may have influenced your psychological development and interpersonal relationships.

Embrace Your Uniqueness: Regardless of your birth order position, remember that you are a complex, multifaceted individual. While birth order theory may offer insights, it should not define or limit your potential. Embrace your unique strengths and work to overcome any challenges associated with your birth order.

By approaching birth order theory with an open and curious mindset, you can gain valuable self-knowledge and leverage this understanding to navigate your personal and professional relationships more effectively.

Embracing the Nuances of Birth Order

The birth order theory, first introduced by Alfred Adler in the early 20th century, has captivated the public's imagination for decades. This influential psychological concept suggests that an individual's place within the family hierarchy can profoundly shape their personality, interpersonal dynamics, and life trajectories.

Through our exploration of this theory, we have uncovered the potential characteristics associated with firstborn, middle, youngest, and only children. While these patterns can offer valuable insights, it is crucial to recognize that an individual's psychological makeup is influenced by a complex interplay of factors, including genetics, socioeconomic status, parenting styles, and life experiences.

As the ongoing debate surrounding the empirical evidence for birth order theory continues, it is important to approach this topic with a nuanced and balanced perspective. By reflecting on your own experiences, observing family dynamics, and seeking professional guidance, you can gain a deeper understanding of how your birth order may have influenced your personality and relationships.

Ultimately, the power of birth order theory lies in its ability to provide a framework for self-discovery and personal growth. By embracing the nuances of this concept and recognizing your own unique strengths and challenges, you can navigate the complexities of life with greater self-awareness and empowerment.

This article was created using AI technology.

Original article: Birth Order Theory: How Sibling Rank Influences Personality and Behavior

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