Why is my brother such a retard?

Ok, so one day, one of my parents were sleeping. He keeps humming this retarded song. I tell him to stop. As a result of telling him to stop, he hums louder. I wanted to knee him in the stomach at that point. I said stop trying to wake our parents up, why are you being such a jerk? Then his reply is "You're a jerk" So I go up to him and he does this retarded face of him tilting his face and expanding his eyes. And he just keeps annoying me... Im 16 he is 10... Sometimes, I really want to just shove him into a wall and beat him down.