Attention all you brothers and sisters out there.
Chances are you’ve been swayed to consider birth order as the be-all and end-all influence on your personality. You know, if you’re the oldest sibling, you are super responsible, more conservative. If you’re the middle child, you like to please. If you’re the baby, you’re spoiled, sociable.
Surprise! The findings of a study conducted by the University of Illinois at Urbana-Champaign and published in 2015 confirmed that, yes, there are indeed differences in personality and IQ associated with birth order, but that the differences are so small as to have no practical impact.
“You wouldn’t notice these differences by talking to a firstborn and a later-born who are the same age,” said Rodica Damian, lead author of the study, an assistant professor of social psychology at the University of Houston.
A slew of books have perpetuated the so-called birth-order effect. When I wrote The Sibling Connection, the experts I interviewed and the majority of studies I reviewed, debunked the birth order myth. Yes, it counts for something, but there are a host of other factors that help shape siblings and the adults they become: gender, growing up with all boys or all girls, age spacing, family pattern over generations, parents’ attitudes, societal expectations.
Taken alone, birth order is is no more predictive than your astrological sign.
The Illinois study examined data on 377,000 US high school students. The data was detailed enough to allow researchers to control for factors such as number of siblings, socioeconomic status, family structure, age, and gender, which some researchers believe may have skewed the results of past studies.
As reported in her Boston Globe article, “Does Birth Order Affect Your Personality?,” Ami Albernaz writes:
Among the slight personality differences the researchers found, firstborn children were more conscientious and agreeable, and less sociable and neurotic, than later-born kids. Yet though these differences were statistically significant, they were so small as to be meaningless, the researchers wrote. Firstborns also had slightly higher IQs, but this difference — about one point — was also not enough to be perceptible.
Debunking the birth order myth will not be easy. The concept has dominated discussions about siblings since 1961 When Walter Toman got the theory off and running in his book, Family Constellations: Its Effects on Personality and Social Behavior. (Toman also has portraits of the male only and female only child.)
You can do your part to set the record straight: When someone asks, “Are you the oldest, middle child or oldest?,” suggest that, sure, they can make some assumptions, but that chances are good that you are so much more.