hmm, if one of the kids aren't one of your own that's a tough one. My daughter was quite horrified that I had the sex chat with all of her friends boys and girls when they were about 16. But they did come to me with questions and concerns. I think if it were me I'd speak to the boy. He's the one that's going to get into the most trouble. I don't know what state you live in, but the youngest concent age I've heard of is 16. So if they are having sex, statutory rape is a definate concern.