My 2.7 DS has started hitting. The cats, other children, us. Not sure how to punish him. Tried the naughty step. Tried getting down to eye level and saying no. Tried smacking his hand (if you hit me/the cat/other child then I'll hit you) I've tried distracting him. Nothing is working. I've reinstalled the baby gate so the cats get some peace upstairs but just not sure how to handle him. I know it's common behaviour but it's driving me mad. Any ideas how to get through to him?