This is learned behavior. When there is violence at home, this is what the child learns - when you are upset at someone, you beat them up. She probably had this demonstrated on her and in front of her over and over growing up. It's very sad and it's a cycle that needs to end.

They should come down hard with her sentence. It's the right thing to do, even if she's that young. Her family needs to see what kind of child they have turned out and that it is not an acceptable way to raise children. No one will learn from this incident if they do not.