The second-born child’s reputation is not always the greatest, and now there is research to tell us why. A study conducted by MIT economist Joseph Doyle suggests second-born children are more likely to be troublemakers. The details of the study even state that the likelihood of bad behavior doubles if the second-born is a boy.
"The firstborn has role models, who are adults. And the second, later-born children have role models who are slightly irrational two-year-olds, you know, their older siblings," Doyle said.
In addition to the second-born’s looking up to their older sibling, parents generally spend less time with the second-born child compared to the first-born. The reduced time spent with these children during their early childhood is found to make a difference in their behavior.
More on this study here.