My son is 3yrs 3mos old. I have a nephew who is 2yrs and another that is 20mos. Both of my nephews have an interest in their penis. They touch it when the diaper is off and while in the tub. My son however does not. He knows he has one (he has a name for it). He'll glance at it sometimes (we are trying to encourage potty training and I think he is trying to figure out how to make it work). Anyway I hear about boys "discovering" it but he just ignores it. Any reason for concern?