I have three - told them the truth. It worked for my daughters, worked some for my son. One of the big issues was "parties" and I just said no. They asked why. I told them that I knew them and did not think they would find it especially fun to watch their friends and themselves drink and ralph on other people's shoes. I actually described a few parties I had been to and all the graphic details. They believed me and decided not to go to parties until they were old enough to leave on their own power whenever they wanted. I just told all of them the graphic truth (my mother did not tell me and let me learn everything on my own - that was not such a good idea either in my opinion and she could have saved me a lot of grief if she had only spoken up. My son did drink when he was 18, but only at someone's home and says he did not drive. I believe him because he is now 37 and has no reason not to tell me the truth anymore. So, tell what you feel comfortable with. I think parents can have a big impact on their children when they are honest.