If we let them.
Through over 200 experimental pairings of nice and mean puppets, researchers at Yale have found that 9- and 14-mo kids like to see cold justice dealt to all those who dare to differ from them in any way.
One might be tempted to see this as a normal step in the development of the self and of building a kid's understanding of the basics of human interaction and culture.
But that's probably just what the manipulative little monsters want us to think so we'll give them all the organic plums.
Abstract: Not Like Me = Bad | Infants Prefer Those Who Harm Dissimilar Others [psych sci via sciencerecorder]
Researchers: Babies prefer individuals who punish those who are not like them [sciencerecorder]