Birth Order Determines Personality? It’s A Myth

Anyone with siblings knows they can differ from us in maddening ways. They share our parents and our family history, but their personalities can be so different. Birth order offers an intuitively appealing explanation for these perplexing differences.

The only problem is, it’s a myth.

Psychologists have speculated on the effects of birth order on personality for well over a century. Sir Francis Galton – pioneer of statistics, fingerprint analysis, weather maps and arithmetic by smell – supposed that firstborn children benefited from greater responsibility and undivided parental attention. As a result they were over-represented among high achievers.

Alfred Adler, protégé of Sigmund Freud, argued that the dethroning of firstborns by younger siblings left an enduring impression on their character.

Firstborns, he argued, feel weighed down by responsibility and have neurotic and authoritarian tendencies. Laterborn siblings are often overindulged and seek creative alternatives to conventional achievement.

Frank Sulloway’s Born to Rebel, published in 1996, made the strongest case for birth-order effects on personality. Referring to the popular big five personality traits, he proposed that firstborns tend to be more conscientiousness and neurotic than laterborns, are less agreeable and less open to new experiences. In essence, firstborns are anxious conservatives and laterborns are easygoing rebels.

Scouring the historical record, Sulloway found that laterborns were more likely than firstborns to support the French Revolution and the Protestant Reformation. They were also more likely to be at the vanguard of scientific revolutions, such as Darwin’s theory of evolution.

These links between personality and birth order ring true for many people. But decades of research have failed to show any consistent and substantial association between birth order and any personality trait.

Two studies published this month should drive the final nails into the coffin of birth-order effects.

In the first study, published today in the Proceedings of —> Read More