I think the wise approach is to be open and honest with your son. You were in his shoes once so you have an idea of how he may feel on the subject. The 'sex talk' is uncomfortable for everyone.. both father and son. Look at it as an opportunity to share who you are and your life experiences and the wisdom you've gained. Who knows he may end up seeing the person behind the 'dad' in whom he can confide and communicate openly with. I also feel that this falls under the 'father/son confidentiality clause'.