My DS1 is 3yrs and my DS2 is 3 months, all was fine up until a week ago. DS1 acting strangely, possevively all of a sudden when baby is in the room with him. Today just topped it, I was in the kitchen warming some milk up with baby in his bouncy chair and out of nowhere DS1 says "mummy 's head" and bops him when with a wooden xylophone banger thing. He didn't do it in a rage or temper, everything was fine, it was like he was thinking about it and just do it. Luckily baby calmed down and I really told DS1 off but I mean if I keep telling him off, he will just be more resentful but I have to tell him off and make him feel bad otherwise he won't know that he is doing wrong. We do spend time with them each individually, my husband works shifts so normally we are both there for them all of the day. I just don't understand DS1 sudden reaction to the baby, he's normally so loving and giving him kisses, has anybody else experience this delayed reaction to a new baby?