Darth Vader

About a month ago my mom bought these cute kids Star Wars books and Bear has been totally obsessed with them (there are 3 of them and they're actually pretty long).  We read them each at least once a day when she first got them and he memorized many pages.

This page in particular has been giving me grief!

Almost every time we read it, he asks me the same question.  I was really caught off guard the first time he asked and wasn't sure how I wanted to answer... For now, since he's only 4, I just tell him that they grow in Mommy's belly!
Dang you, Darth Vader!