Birth Order

Birth order, also referred to as position in the family, is the timing of an individual's birth within the family structure. The effect of birth order on personality development has been the subject of increasing social science research from the late 20th century to the present. While factors such as gender, age span between siblings, cultural practice, parenting styles, and genetic makeup affect personality traits, statistical studies show that birth order also may play an influential role in the shaping of behavioral patterns lasting into adulthood.

One of the first to examine the dynamics of family structure was Austrian psychologist Alfred Adler (1870–1937), founder of the school of individual psychology. Adler believed that the relationship with siblings often foreshadowed later individual outcomes. His general hypothesis purported that oldest borns suffer from a degree of neuroticism stemming from the arrival of the second child, which diverts attention from the first. Later borns, he believed, are overindulged, and the middle borns are most likely to develop successfully. However, he produced no long-term scientific research to support this theory.

Common anecdotal wisdom has often emphasized stereotypical negative traits based on sibling order, describing the oldest as domineering, the middle as neglected, the youngest as spoiled, and only children as selfish. However, research based on long-range data contradicts these widely held but unsupported beliefs and demonstrates a complex cause-and-effect association. Comprehensive research has sought to discover a correlation between birth order and a wide array of social factors, including personality type, career choice, success in marriage, and receptiveness to new ideas.

Of particular interest to mid-20th-century investigators was the discovery of factors leading individuals to succeed in certain career fields, especially those requiring decision making under pressure. Such high-profile positions examined included U.S. presidents and astronauts participating in the early stages of the U.S. space program. Data reveal that 52% of American presidents have been first- or older borns and 21 of NASA's 23 first astronauts who flew into space were either the oldest or only children; all 7 of the original Mercury astronauts were also firstborns. Other studies show that prominent television newscasters and talk show hosts are often firstborns or only children. These data have led to conclusions linking older borns and only children with a high potential for achievement and leadership as well as possessing a desire for approval. Higher-than-average scores on verbal performance by only children and firstborns have [Page 94]also been attributed to a greater amount of time spent in the company of adults.

Research led by psychologist Frank Toman studied the impact of birth order on marriage, friendship, and gender roles, with emphasis on the variables of the sex of the siblings and birth spacing. Toman and his colleagues surveyed mid-20th-century European families to determine the success of marriages based on birth order of partners and the sex of their siblings. Their findings concluded that marriages were most likely to succeed between the older brother of a sister and the younger sister of a brother (or the reverse). These he called complementary sibling roles, which prepared the partners for a similar role in the marriage relationship. Persons who married a counterpart—such as the oldest in the family with same-sex siblings—were more likely to divorce, because the partners compete to play the same role rather than complement one another. Toman's theory is widely recognized in marriage and family counseling and has been used as one of a number of tools to measure compatibility.

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