Isabella (five-years-old): Daddy, girls can have babies, but boys can’t.
Me: Well, uh, yes, Honey, That’s right.
Iz: Because boys have something between their legs to stop the baby from coming out. What is that thing?
Me: Well, Honey, you’re right. Boys and girls have different bodies. You see…
Iz: Did you know that sometimes the moon is big and sometimes it is small? Why is that? And, where do the stars go during the day.

Me: (Whew… Not yet…)

Almost verbatim.