Science Says Second-Born Kids Are Most Likely to Behave Badly, Even Into Adulthood

Second-born boys, specifically, are more prone to behavioral problems starting in childhood, according to a new study on how birth order affects kids.
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We already know that second-born kids tend to get less attention than their firstborn siblings (or so the stereotype goes). This was definitely true in my house in the early months and years of my second daughter's life, quite simply because I had less time to focus on (some might say obsess over) every little thing she did, now that I was a mom of two. But hey, that's a fact of life when you have more than one kid, right?

But now, a new study from MIT economist Joseph Doyle sends moms like me on a slight guilt trip as it finds that a second-born child tends to have more behavioral issues than a firstborn. The reason? As researchers explain, "We consider differences in parental attention as a potential contributing factor to the gaps in delinquency across the birth order."


Doyle and his team looked at thousands of families in Denmark and Florida, and determined that a child, born second in a family is typically the biggest troublemaker. But that's not all. Beyond determining that second-borns are more likely to, ahem, challenge their parents in early childhood, boys in particular are also more likely to have problems at school, and even with the law. Specifically, according to Doyle's paper, "second-born boys are on the order of 20 to 40 percent more likely to be disciplined in school and enter the criminal justice system compared to first-born boys even when we compare siblings."

Whether you're firstborn, middle child, last-born, or only child, birth order can have a big effect on your personality and behavior.

So that's not great news.

But consider that this certainly isn't the first study to look at how birth order affects kids' personalities. And I don't doubt there is something to this type of research. But, what was found here, and in many other cases, does not hold true in our house, and it may not in yours, either. For instance, it's actually my third child who is a real pickle, not my second. And in fact, my second child has been the easiest one from the start!

She's a people-pleaser and will go out of her way to compromise with her siblings so everyone can be happy. She's sweet, considerate, and for the most part, even-tempered. Sure, she has some challenging behaviors, like the fact that she basically refuses to eat anything other than yogurt, but she's certainly no more difficult than my other kids. To be fair, she is a girl, and girls weren't necessarily the focus of this latest study.

In the end, I'd caution parents not to worry too much in light of this data, but rather, to keep it in mind. And don't be too hard on yourself, or panic if your second-born is throwing a temper tantrum as you are reading this! Instead, the takeaway here seems to be that if we know second-born kids—and boys most likely—will have a greater likelihood of delinquent behavior, we as parents can make it an action point to spend more time focused on them, paying attention to how their behavior evolves, and work proactively to keep them in check, so to speak.

What's your take?

Melissa Willets is a writer/blogger/mom. Find her on Facebook and Instagram where she chronicles her life momming under the influence. Of yoga.


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