you deserve to let this go. it sounds like you were just curious. as you said, no one was really seriously affected by it (and if they had been, i think they would hav let you know that by now). personally, i think 4th is a little old to still be touching ppl, and i think its odd that your mother labled those actions as "normal". but what is done is done. and while you cant change the past, focus on the future. you know its wrong now.

if you are still beating yourself up about it, talk to someone about it. it might be interesting to try and explore if there was an underlying cause? maybe an impulse disorder, etc.