But selfishness is a LEARNED behavior.People say that about lying, too. But as soon as a child learns to speak, they know that there are some things that mommy doesn't want to hear. Like she doesn't want to hear that Little Johnny ate the cookies, so he'll of course say that he didn't ... while he's still chewing them.
People say, "like taking candy from a baby." Have you ever tried that? It ain't easy. And they won't like it. So even before they can talk, children understand about having things taken away from them, and they don't like it. Just like they don't like being told they can't have something they want. How is this not selfishness?