Second-Born Kids More Likely to Exhibit Troublesome Behavior Than Their Siblings, Study Finds

Furthermore, second-born boys are "20 to 40 percent more likely to be disciplined in school and enter the criminal justice system" than first-born boys

Two happy sisters on a road trip
Photo: Getty

Attention all individuals with one older sibling: You might want to reevaluate your next step.

According to an in-depth study by researchers from MIT, Northwestern University, the University of Florida and more, second-born children — and, more so, second-born boys — are “20 to 40 percent more likely to be disciplined in school and enter the criminal justice system compared to first-born boys,” when discussing boys alone.

The research was conducted on subjects in Denmark and Florida, finding results that were “remarkably similar
across the two locations” and taking into account “measures of infant and childhood health, parental investments, school quality and sibling composition,” according to the paper.

One interesting tidbit of information, the study found, is that “maternal employment and the use of daycare is higher for second-borns in years 2 to 4 compared to older siblings” — suggesting a longer amount of parent-to-child face time could contribute to a less trouble-making future.

Want all the latest pregnancy and birth announcements, plus celebrity mom blogs? Click here to get those and more in the PEOPLE Parents newsletter.

Mom with baby looking at plane at an airport
Chris Tobin/Getty Images

“While [first-borns have] undivided attention until the arrival of the second-born, these results show that the arrival of the second-born child has the potential to extend the early-childhood parental investment in the first-born child and a concomitant bifurcation of parental attention between first- and second-born children,” the study continues.

In an interview with NPR, MIT economist Joseph Doyle, one of the authors of the paper, said he found “the results to be remarkable that the second-born children, compared to their older siblings, are much more likely to end up in prison, much more likely to get suspended in school, enter juvenile delinquency.”

“Across all these outcomes, we’re getting 25 to 40 percent increases in the likelihood of these outcomes just by comparing a second-born sibling compared to a first-born,” he revealed.

Two happy smiling little boys
Brothers posing for a photo. Getty

RELATED VIDEO: Former Bachelorette Ashley Hebert Rosenbaum Opens Up About Her Sibling-Rivalry Fears

Another explanation? The constant presence of a younger, less mature “role model” for a second-born child — in their older sibling, as opposed to just their parents.

“The firstborn has role models, who are adults. And the second, later-born children have role models who are slightly irrational 2-year-olds, you know, their older siblings,” Doyle told NPR.

“Both the parental investments are different, and the sibling influences probably contribute to these differences we see in labor market and what we find in delinquency. It’s just very difficult to separate those two things because they happen at the same time.”

Related Articles