Why some animals eat their young

Last night my parents and I went to A&W for some coney dogs and we decided to eat inside (which was nice because the backseat of the bug has no room) and a mom and her son were there because they'd ridden their bikes. Well, I thought that my cousin Michael was Satan incarnate. Was I ever wrong. This child blows Michael away in that category. Demon Spawn was yelling that he wanted Mountain Dew and Sprite which they didn't have. He was hitting and pinching his mom, had no clue what an inside voice was and everything was all "WHAT THE HECK?" instead of asking politely what something was. My dad even tried to get him to shut up because he slipped into bus driver mode. Man. I never would have behaved that way in public, I would've paid for it.