I also agree just to treat it as any other anatomy/physiology question.

At the same time I'm happy nobody understands what DD2 is talking with us when we are out in public. She has not asked yet those questions but she is very interested about different genders. She knows there are boys, girls, men and women and so sometimes at the playground she might comment "Mommy, boy is coming, he has a penis, he is a boy" or even worse she sometimes thinks some more manly looking women are men and tells me "He is a men and has a penis like daddy, I'm a girl like mommy and I have vagina" You can only imagine how embarrassed we would be if that WOMAN would understand that our little girl thinks she is a man with penis .

She is also really interested how you eat food, where it goes from your mouth and how poop comes out. She is constantly wondering (and commenting) what happens to ppl's food.

Like I said, these are the times we are thankful she is bilingual!