I think that it comes from the lack of consistency on the part of the parents. Many parents give in to their children too much. Little Johnny has every video game, gaget, toy, whatever that he asks for. I think that kids it this situation do not know what limits are. Mom and Dad never say no or tell the kid that they have to work for something. What they want, they get. I have seen kids without discipline who talk any way that they want to their parents, especially mom, without repercussions. I can see this lead a child to express anger in violent ways. They do not understand that there are consequences to their actions. They do not understand that killing someone is bad and that you have to go to prison for this. Not saying no to your kids leads to self-centeredness, it’s all about me.