Small children aren’t great at sharing, as any parent or preschool teacher knows. But little kids get cut a lot of slack on the presumption that they don’t know any better.

Well, the jig is up. Researchers have found that 3-year-olds know darned well that sharing is the right thing to do. But when given the chance to share stickers with another child, they hoarded instead.

That flipped around by age 8, the children shared stickers, giving half to another child.