I'm tempted to teach DD a very bad thing

emilykristene2006

DD is 3 1/2 and DS is 15 months.

DS is always smacking DD, pulling her hair and even biting her.

She was just trying to read him a book so I can get dinner started. He kept trying to smack the book out of her hands. Then he reached up and yanked her hair. 

I am so temped to tell her to do it back to him when he does it again. Of course I won't tell her, but I'm tempted!

How do I make it stop???