Here's a great way to permanently traumatize your kids. Give them some of these creepy Amamanta anatomically correct dolls:

These dolls include true anatomical details such as stitched on genitals and breasts. This means that children and parents alike will find the dolls true-to-life and see themselves as naturally complete and OK... Amamanta family cloth dolls are soft and cuddly and consist of a mother, father, son, daughter and newborn baby. This newborn baby can be placed in the mother’s belly and pulled out of the mothers womb to demonstrate birthing to the child.

I think what makes the dolls creepy is that they look totally fake, with painted on eyes and smiles, and then they surprise you with these ultra-true-to-life bits sticking out. It's disconcerting. My idea is that you could have your kid open them as a present on Christmas morning, and then, with the entire family there (aunts, uncles, and everyone), initiate a frank discussion about genitals and the process of birth. The kid would never be the same. (And a warning in case you're reading this at work: If you search around long enough on the amamanta site, you will encounter pictures of naked dolls.)