There’s overwhelming consensus that breast-feeding is the optimal way to feed an infant. It has many known health benefits, but there’s still debate about how it may influence kids’ behavior and intelligence. A new study finds that children who are breast-fed for at least 6 months have less hyperactive behavior by age 3 compared with kids who aren’t breast-fed. But the same research also finds that breast-feeding doesn’t necessarily lead to a cognitive boost. The study of 8,000 children in Ireland found that overall, the breast-fed kids score a tad higher, but the difference isn’t large enough to be of any significance.