I did it with my son..hes 14.his dad isnt very good with talking about stuff like that and I think my son would of felt weird if he tried.I have always had an open relationship with my son to where he can ask me anything and I think thats important because 1 you kind out more about what they are doing or are interested in doing and 2 you know you are the one giving the info on topics so its legit! My best advice is to go with the parent they are most comfortable with talking things about,bring each seperately at different times and tell them just if they have any questions to ask you..its natural and your not accepting him doing it but you know it will happen so you want them to know the right info.dont get shocked by any questions they have otherwise they wont speak again.I dont think you have to get into the whole baby sex thing..there is health class and unless they are home schooled they provably no more than you think....just let them no you are there for them!good luck and excuse if some words are misspelled i dont have my glasses on and just typing!!!!