RP : Curiosity about private parts

jshf

DS1 has gotten very curious about private parts. We've found him showing his penis to his female friends and also looking at their parts. He has been playing "going potty" with them too. We have bought different books and talked to him about curiosity being normal but that we need to respect people's privacy and not to ask girls to see their parts or to show his private parts either. He loves Amazing You and we thought that would help lesson the curiosity. 

We are trying to be very careful to not make too big a deal or to shame him or something like that. But it seems like any time he has a Playdate with a girl they are trying to hide and to look at each others private parts. My husband wants me to take ds1 to a doctor but I would love any feedback you ladies could give. Have you dealt with this with your children? Any positive suggestions? Thank you!