Hi, sounds like an unerving dilemma. Have you spoken with a counselor? Social worker, psychologist, family counselor familiar with child behavior. The fact that your daughter was clothed and open to telling you sounds as if she were not threatened as is often the case. speaking with a counselor can help you understand the childresn's behavior (specifically your son's)how normal or abnormal it is, and deal with your feelings about it and help you frankly and openly deal with it openly with both your children. did you tell your children why they are not being left alone with one another? Openness on your part is important. Keeping this secret only gives it more power. As a child I was sexually abused by an adult. It has affected me in many ways. I have gone to counseling for many years. The most important thing (in my opinion)is for you to become as comfortable and educated as possible within reeason in order to openly and effectively work with your children and not perpetuate a secret. Your son may only be curious, however this does sound inappropriate, a counselor can be a voice of reason and objectively help quell the panic you feel. It's not like we get manuals for how to deal with these things in our life. Just as you take a class or have someone teach you how to drive, at times we need anothers expertise to guide us in how to deal with situations in which we have no experience. Best to you and your family in finding the solution that is right for you.