D.J.
HI Rana,
We have 2 girls and a son (he is the youngest at 5). We have discussed that everyone has private parts. We have told them where they are and that only a mom or dad or doctor is allowed to look at them.
We also answer any of their questions as they come up. My daughter at 3 wanted to know how her sister was going to come out, so we told her. My son has also had similar questions. Just be up front and straight with him, he will be fine.
D.