The Other F-Word by Natasha Friend

When a severely allergic teenager decides to track down his sperm donor in order to do genetic testing, he ends up with more than he bargained for: a passel of half-siblings, too.

I loved this book - it does a stellar job dealing with all the conflicted feelings about "genetic source material" since there are so many diverse families involved: the book includes lesbian parents, heterosexual parents, mothers who gave birth and mothers who did not, kids with siblings, singletons, and even twins who disagree about this life-altering decision. There's a best friend who's adopted, which allows a conversation about the decision to donate sperm versus giving away a baby. The kids are teens - so they're a bit more adult in perspective and yet still very involved in family units. They're in turn curious, scared, anxious, and unexpectedly delighted to find someone with whom they share DNA.

And in spite of all these emotions and potentially heavy subject matter, it's a quaint book that's funny and utterly captivating. I'm not giving too much away to reveal the story's also about teen crushes, bullying, troublemaking/underachieving, and childish grudges. Highly recommended.