Why Everything You've Heard About Birth Order Is Basically Wrong
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Firstborns grow up to be successful carbon copies of their parents, while youngests are dimmer and more rebellious. And middle kids? They’ll do whatever they can to grab attention.
These timeworn tropes about birth order affect how parents treat their kids, how health officials target prevention messages, and even how law-enforcement officials decide who’s likely to commit crimes. But new research suggests these stereotypes don’t hold up to scientific scrutiny. (Looking for more health tips and advice? Get your FREE trial of Prevention + 12 FREE gifts.)
In a new study published in the Journal of Research in Personality, a University of Illinois team found only minuscule differences between IQ scores and personality traits based on birth order. The effect was so close to zero that it was more or less meaningless, says lead author Rodica Damian, PhD, who’s now at the University of Houston.
Damian says her study’s massive sample size—nearly 400,000 high schoolers—bolsters its accuracy. More recent research also pokes holes in those common convictions about conservative first children, spoiled youngest sibs, and everyone in between.
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Intelligence: Some older reports seemed to suggest firstborns had higher IQs. But, given a close read, even those tended to side with the latest research, says Brent Roberts, PhD, another of the U of I study’s authors. Case in point: A 2012 analysis of 17,000 British children in the journal Personality and Social Psychology found oldests tended to be a tick sharper—but not if you adjusted the data based on family size.
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Delinquency: Popular beliefs hold that middle children commit more crime, in part to stand out from their older siblings. Eldests, meanwhile, walk the straight and narrow, seeking to uphold family values and curry their parents’ favor. But a 2013 study in Personality and Social Psychology Bulletin blows up those preconceptions. The study looked at marijuana use, nonviolent crime, and binge drinking in teens. The results show any birth-order effect disappears after factoring in things like family income, education levels, and parents’ ages.
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Willingness to take risks: It makes sense that later-borns would be risk-taking rebels. After all, they have to blaze their own path to stand out from their older brothers and sisters. But just because you know (or have) a family that fits this pattern, doesn’t make it universal. So says Philipp Sand, MD, of the University of Regensburg in Germany. His paper, published last year in the Journal of Health Psychology, compared extreme-sport participants (think BASE jumping and freestyle snowboarding) to regular college students. It found firstborns engaged in risky behavior as much or more than their little brothers and sisters.
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All of this research makes you wonder: Why do false beliefs about birth order persist? Because they’re brought up again and again, we tend to notice those people or families that fit our preconceived notions. “We weigh anecdotal data and personal experience too heavily in our thinking,” Roberts says.
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Another factor—one that’s plagued past research on the topic—is that parents answer questions about their children’s personalities based on their current ages, and don’t consider how older kids behaved in the past. “The firstborn may always appear more conscientious if we don’t take age into account,” Damian says. In other words, that rebellious teen may soon grow into a responsible adult—just like his or her older sibling.
Whether you’re an oldest, a youngest, or a tweener, consider yourself free of the burden of birth order.
By Cindy Kuzma
This article ‘Why Everything You’ve Heard About Birth Order Is Basically Wrong’ originally ran on Prevention.com
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