Buzz
Since Freud's time, psychologists have sought to understand how birth order shapes our lives, claiming that youngest children tend to be either more rebellious or more agreeable, while oldest children are often seen as more conscientious or intelligent. However, many factors complicate studies on sibling dynamics, including family income, parental education, and whether you're the youngest of two or five siblings or have an older brother compared to an older sister.
In a recent, large-scale study conducted by psychologists from the University of Illinois at Urbana-Champaign, it was found that being an older or younger sibling has nearly no effect on your personality or intelligence. The research, published in the Journal of Research in Personality, analyzed data from 377,000 high school students in a national longitudinal study that started in 1960. While there might be tiny personality differences between firstborns and later-born siblings, they are negligible.
The study indicated that firstborn children might be slightly more extroverted and conscientious, though the differences were very small. The IQ advantage for firstborns was described as “almost imperceptible.” When compared to other personality and intelligence factors like family income, the impact of birth order was nearly undetectable. The researchers concluded that “the attention given to the role of birth order on personality is, at best, disproportionate to its importance in shaping personality differences among siblings across families.”
The study had some limitations, such as relying on self-reported personality traits instead of observed ones and not accounting for significant age gaps between siblings (growing up with an older sibling already living independently offers a different environment than having a sibling just a few years older). However, since this is one of the largest studies of its kind, it is likely more reliable than previous research that found notable personality differences among only a few hundred or a thousand participants.
