Along with the other info, only child, and getting what he wants, you may want to consider to Mom to just say "no" sometimes as well. It seems kids with this behavior often get everything they ask for, therefor have the mentality that everything is theirs. Ask her if she is willing to tell him "no" even when she can give him what he asks for, he needs to learn he doesn't always get what he wants. For example...if they are in the grocery store and he asks for a box of fruit snacks, (I am willing to bet, she usually doesn't see the harm in giving in and letting him have them) ask her to say, "no, not today", he needs to learn to deal with not getting....