Admit it: You’ve bought into the idea, at one time or another, that birth order really matters. It’s fascinating to consider the idea that the reason your children’s personalities are so different has to do with where they’re positioned in the nuclear family tree. And the stereotypes, so often on-point anecdotally, can be convenient. Your oldest is so (studious, responsible) because that’s the way firstborns just are. Your baby will always be (vivacious, goofy) because she’s, well, the baby. As for your middles—forget it. They may be making their own pancakes by age 2, but their (feelings of isolation, neglect) might cause them to fly the coop and never look back at age 22.
But a big new study deflates some of the most common beliefs about the effects of birth order on children. Researchers from the University of Illinois at Urbana-Champaign studied 377,000 American high school students, a massive sample size relative to other birth order studies to date. The study was controlled for such potential confounders as family’s economic status and number of children. The team found:
-Firstborns do have a higher IQ than later-borns, but by just a single point—a statistically significant but, according to researchers, meaningless difference. The strongest association in terms of cognitive trends was for higher verbal ability in firstborns, but the correlation—of just .08—was still too small to matter much.
-Being born first was also associated with being slightly more extroverted, agreeable, and conscientious, as well as (surprisingly) less anxious, according to their data. But these personality correlations are, like IQ, too tiny to matter in real life. “You are not going to be able to see it with the naked eye,” one researcher explained. “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 researchers’ takeaway? “The message of this study is that birth order probably should not influence your parenting, because it’s not meaningfully related to your kid’s personality or IQ,” the study’s lead author, Rodica Damian, Ph.D., said. In other words, we shouldn’t expect—or explain away—certain behaviors due to our kids’ position in the family. This provides some helpful perspective for me, as the mom of three boys with very different abilities and personalities. There have been times when I’ve attributed one kid’s strengths or weaknesses to birth order; and other times when I’ve wondered why my oldest isn’t more detail-oriented, or my youngest isn’t “easier” (i.e., living up to the more positive birth-order stereotypes). Fact is, they’re all delightfully complex—and life is, on all but the craziest days, all the more interesting because of it.