I was 12 the first time I had sex because I wanted to. He was 16. (I actually lost my virginity at a very young age because I was abused but I don't count the abuse as losing my virginity. It was stolen from me.)
As for what the original poster said about being 12 and having sex with a 28 year old...while it's not something that's acceptable, it does happen more often than people realize. We don't know the situation that led to this relationship. If the woman was very lonely and didn't have a man to turn to it's very likely that she did turn to a boy. And what boy/young man wouldn't brag about being with someone older at that age? I'm not saying that this was right. In fact living through what I have I find it very wrong, but if the young man's experience didn't leave him mentally, emotionally, or physically scarred then we should just let it go. It's not like he can go back and undo it. Live and let live.