My 5 year old daughter and 3.5 year old son share a room. Lately, they have started to really notice and comment on each other's private parts. Especially my daughter who points and laughs every time she sees my son's. We do not bathe them together but this happens usually when they are getting dressed or undressed in their room. What should my expectations be at their age/stage, what boundaries do we enforce, and what attitude do I need in regards to this?