Birth Order Effect on Personality Development



The long term

influence of a child’s birth order has been a deeply debated and thoroughly

researched aspect of developmental psychology. Society has embraced birth order

theory as popular psychology and many psychologists agree that influence of

birth order shapes our later life choices which impact our social interactions,

choice of professions and relationship strategy. Critics of birth order theory

argue that changes measured in later life are shown that can alter the previous

influence of the birth order, therefore this contradiction would indicate that

birth order is a temporary environmental influence which can be eliminated by

later life environmental changes rather then a steady biological factor of

imbedded trait development.


Birth Order Influence on Childhood Personality Development


Austrian Psychoanalyst Alfred Adler published initial

papers on Birth Order Theory in the early 1900’s. Adler defined his theory that

the oldest child’s personality develops differently after he is “dethroned” by

the next child who then becomes the new focus of his parent’s attention, he is

then assigned a unique role as a surrogate parent to help raise his younger

siblings at the sacrifice of his own self interest. The youngest child or only

child does not grow through a period of mentoring subordinate siblings and

therefore lacks some developmental character building experience into adulthood

(Adler 1928).  For many years since birth

order stereotypes have been a common household belief, society had previously

found little reason to question the early scientific studies that reaffirmed

Adler’s original concept.

However more recent research pointed out a lack of

consistent evidence for birth order influence on adult personality on a large

scale. And studies in late adulthood fail to find remaining influences of birth

order behavioral traits. Using more precise scientific controls for statistical

reliability, modern researchers have failed to produce statistically

significant evidence to support these widely believed stereotypes of birth

order behavior (Paulhus, 1998).

Birth Order Traits

Oldest Child Traits

Oldest children are observed to be

intelligent, energetic, logical, ambitious, enterprising, conscientious,

punctual, scholarly, socially conservative, emotionally neurotic and self

confident. Eldest children have shown a measurable intelligence advantage over

their younger siblings. The intelligence advantage is reliably supported when

contrasted against only children who did not share this measurable intelligence

advantage over the population as a whole. The theories for the eldest advantage

typically attribute it to the intellectual development gained from tutoring

younger siblings early in life (Ernst, 1983).

Eldest most often pursue goal oriented

accomplishment to demonstrate superiority in competitions of social ideals to

win affection from parents. Over 70 percent of entrepreneurs, 90 percent of

astronauts, 80 percent of Nobel Prize winners and 65% of American presidents

were eldest children, and these statistics climb dramatically as we adjust for

second born who are the oldest male in a family. They are consistently found in

leadership occupations, have the highest rate of military service, and are

dramatically overrepresented in political, law enforcement and corporate

leadership; they also dominate precision sciences such as law, medicine and

engineering. They exhibit a higher then average resistance to change, and are

most likely to demonstrate aggression when met with resistance from

subordinates (Sulloway 2001).  They are

found in measurably low concentrations in fields that offer limited structure

and instead reward creativity such as sales, advertising, art and music.

Middle Child Traits

Typical middle child traits are measured to be

cooperative, flexible diplomatic mediators of social conflict. Middle children

also self report the highest scores of suspicion, mistrust and cynicism of

intentions of their superiors; however they have the highest loyalty rating to

their subordinates of any birth rank (Sulloway, 2001).

Middle children never enjoyed the unique period of home life

as an only child like the eldest and youngest enjoy at some point. To

compensate for this hardship, middle children focus on developing a supportive

social circle outside of the home, investing their energy cultivating

friendships and alliances with their peers.

Middle children become more financially and emotionally

independent and typically live the furthest distance from the parents later in

life. They are also the least likely to return home for family gatherings or to

ask their parents for financial assistance (Sulloway 2001). Of the trait of

generosity, middles offer their subordinates the highest rates compensation in

the workplace and are more likely to offer acts of reciprocal altruism in

effort to build a team approach to tasks. Middle children have been measured to

rate their childhood as unloving and unsupportive on self-assessment

questionnaires (Ernst, 1983).

Middle children are most likely to enter professions that

require diplomacy, innovation, reward risk, as well as fields which allow creative

latitude in establishing their duties and the pace which the tasks must be

accomplished. Middle children are overrepresented in the fields of fine art,

advertising, sales, mediation, education, psychology and personnel management.

Middle born children have been found to be measurably underrepresented in

military service and strictly structured corporate cultures (Sulloway,


Youngest Child Traits

Youngest children are observed to be the most empathetic,

creative, carefree, liberal, and rebellious. Behavioral testing indicates them

to be risk takers, idealists, witty, secretive and emotionally immature for

their age. They more then any other birth order excel at artistic pursuits

especially the performing arts of acting, dancing and music. They are playful

even as adults and develop a tactful non-confrontational approach to social

interactions often relying on humor and flattery to persuade others to their

point of view (Sulloway, 2001). They have been measured to have some emotional

underdevelopment which may be from lacking the experience of watching a

biological duplicate of themselves at varying stages of maturity as any older

sibling can witness, this unique perspective may be key to a keen emotional


A  study uncovered

an unusually high incidence of homosexuality in youngest sons, Edward Miller

further studied that data on the phenomena in his book Homosexuality,

Birth Order

and Evolution which indicated that the more older brothers a male has, the

higher probability he will be homosexual. This birth order sexual preference

however has not found a measurable correlation to females in either the number

of older sisters the male has or any measurable influence of female

homosexuality (Miller, 2009).

Only Children

Only children have been measured to mature

faster, have higher verbal test scores, and are perceived as responsible,

self-centered, perfectionists. Only children especially only males demonstrate,

high levels of work ethic and career oriented achievement and are observed to

demonstrate the longest enduring commitment to goals.  While society seems to universally stereotype

only children as spoiled and selfish, a study of over 5000 Chinese families

with only children were compared to peers with siblings, that research failed

to uncover any statistical disadvantage to the long term success of only

children. (Sulloway, 2001)


A study published in the 1980s showed no correlation

between birth order and the big five personality traits of randomly selected

population in military entrance assessments (Ernst 1983). However Sulloway has

found that when studying each individual within a family the influence of birth

order is remarkably defined, however when comparing personality traits across

all members of society that birth order has a very weak influence on

personality traits. Paulhus believes this can be explained by accepting the

fact the birth order is a weaker influence then heredity of behavioral

genetics. This theory could explain why the 2nd born from 100

different families can measure much differently on personality assessments

however still exhibit 2nd born traits when compared with their

siblings within their family (Sulloway, 2001).

Further support of birth order impact on personality was

found in  a 2009 study documented that

first, middle and last born adults subconsciously self segregated themselves

into workgroups when assigned a group project. This natural selection of group

project partners suggests that we have a subconscious awareness in our own

behavioral traits and can unknowingly perceive them in those around us to allow

us to partner up with peers that share our priorities (Miller, 2009).


Adler, Alfred.

1928. “Characteristics of the First, Second, and Third Child”,

Children, 3, 14-52.

Ernst, Cécile

& Angst, Jules. 1983. Birth Order: Its Influence on Personality.

Berlin and New York



Paulhus, D.L., Trapnell, P.D., & Chen, D. (1998).

Birth order effects on personality and


within families. Psychological Science, 10, 482-488.

Miller, Edward. Homosexuality,

Birth Order and Evolution. (February 2000) Archives of Sexual

Behavior No. 29 . 1-34

Sulloway, F.J. (2001). Birth Order, Sibling Competition,

and Human Behavior.


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