The Birth Order Myth, Debunked

I always thought that birth order equals destiny. I’m the older of two children, and I’m driven, ambitious and uptight. My younger brother? The classic second child: mellow, change-averse and hard to motivate. I lived for A’s on my report card; he couldn’t have cared less. I see the same dynamic with my own two kids. Except, do I? Now that I’ve read the results of a new study on birth order, I’m not so sure.

The study was published in the Journal of Research in Personality and came out of the University of Illinois at Champaign. It looked at a very large sample size: 377,000 high school students. “It’s the biggest [study] in history looking at birth order and personality,” said University of Illinois psychology professor Brent Roberts, who led the study alongside postdoctoral researcher Rodica Damian. The study found that sure enough, eldest children are smarter—yessss!—but only by one measly IQ point. That difference in IQ points is meaningless, say the researchers.

They also found that personality traits between first-borns and later-borns are indeed different, like my unscientific (and smug) observation of my sibling had suggested. First-borns tended to be more extroverted, agreeable and conscientious, while children born into the family later had more anxiety. But those differences were “infinitesimally small,” according to Roberts—a 0.02 correlation. “In terms of personality traits and how you rate them, a 0.02 correlation doesn't get you anything of note,” Roberts writes. “You are not going to be able to see it with the naked eye. You’re not going to be able to sit two people down next to each other and see the differences between them. It’s not noticeable by anybody.”

“The message of this study,” wrote Damian, “is that birth order probably should not influence your parenting, because it’s not meaningfully related to your kid's personality or IQ.” Many past studies, they say, have been skewed because parents will report things like “My older child is more responsible.” But of course they are, because they are older.

If there’s no intelligence advantage, and no destiny for first-born greatness, I guess I can live with that. Just don’t tell my brother!