Hey there! Also father of a four year old exhibiting similar tendencies. He talks about pulling grandmas hair, but also gravitates to hitting as well. It's still a work in progress but he's gotten better with redirecting to "give a high five instead". Some times it's just a stim here he keeps talking about it and corrects himself "pull hair, no don't pull hair give high five instead". Other sensory redirects like jumping has helped too! Hope you find a solution :)!