Hi all - looking for a wee bit of advice. DS1 is 3 and DS2 is 15 months. For weeks now, DS1 has regularly been slapping, pushing, nipping and pulling DS2 hair. However, yesterday he punched him full on in the face! When asked why, he replied 'me want to'. Should I be worried? Any suggestions on how to stop him doing it? All advice gratefully received!