Where Willy Went is one of our favorite books these days. The girls had it in the car today when we took my 16-year-old nephew with us to the museum. The girls were waving it in front of him and saying, "Do you want us to read it to you?" He looked at the cover (that's why I put the image here, so you could see it too!), and turned to me and said, "That looks like a sp. . . ." and stopped, worried about saying "sperm" in front of the girls. I said matter-of-factly that it was a sperm -- Willy is a sperm. He was shocked, simply shocked, to learn that his little cousins knew about such things! They wanted to read it to him, but he was far too embarrassed, so I made them stop. And I don't think it helped that his name is William and the sperm is Willy. Tee hee!
But all of this isn't why I like this book about the birds and the bees (ahem). The thing I like about it is that it quite clearly explains the role of the father in the making of the baby. Most books for kids about baby-making focus more on the baby growing in the mom's tummy after a passing reference to the dad planting the seed. For instance, Contemplating Your Bellybutton is a super-cute book explaining the in-utero connection of mother and child, but dad pretty much gets a pass (we saw the book, which we have read countless times, in the museum gift shop, and the girls loved embarrassing William with it. And before bed we had to talk about belly buttons and whether Maya's birth family members have "outies" since Maya does, and whether Zoe's birth family members have "innies" since Zoe does (I don't think it's an inheritable trait -- anyone out there who can confirm that?)).
While "Where Wlly Went" isn't an adoption book, it's great for talking about the genetic contributions of birth parents. As the story goes, Willy is a sperm who isn't any good at math, but is a heck of a swimmer. And when the baby created from Willy the sperm and an egg grows up, she's lousy at math, but a heck of a swimmer. Simple, but a great jumping off point to talk about inheritable traits.
(In the interest of full disclosure, if you buy the book from the link above, I get a kickback from Amazon -- so be sure to buy it from somewhere else if that offends you!)