When I was younger, I enjoyed being the oldest child in my family and wouldn't have wanted it any other way. I was--and still am--what some people would consider a "typical" first-born. Structured and controlling? Yep. Diligent and eager to please? Check. I proudly owned my oldest-child personality, both the good and the not-so-great...until I read a recent study that says birth order doesn't meaningfully affect personality or IQ.

The study, which was led by University of Illinois psychology professor Brent Roberts and postdoctoral researcher Rodica Damian, looked at 377,000 high school students and was the biggest birth order and personality study ever. It controlled for some factors that might have skewed the results, such as the family's economic background, how many kids each family had, and the ages of the kids at the time of the study. While first-borns scored one point higher on IQ-point tests than later-borns, the difference is so small that it is, as Roberts put it, "meaningless." Also unremarkable? Any differences in personality. Yes, first-borns were more "extroverted, agreeable, and conscientious" than later-borns, but not enough to be noticable. The bottom line is that we're not so different, first-borns and later-borns.

The findings are not only interesting for siblings; they are something that parents should take into consideration as well. "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," Damian said.

While it's not surprising to me that there isn't a notable difference in IQ, I admit that the personality bit through me for a loop. My brothers and I fit the oldest child/middle child/youngest child stereotypes to a T. I know it's crazy to doubt a study of this magnitude, but I still believe in astrology, so I can't say I'm always logical. Either way, the study's findings are something to consider when I have my own kids, though I don't think I would have treated them differently anyway (at least not consciously!).

What do you think: Does birth order shape personality?

Hannah Werthan is the associate social media editor for She is married to an oldest child who is the definition of a perfectionist. Follow her on Twitter and Instagram.

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