The Good Vibrations Guide to Sex: The Most Complete Sex Manual Ever Written A great resource for your teens (and you) when they are ready to find reliable answers for themselves.
S.E.X.: The All-You-Need-to-Know Progressive Sexuality Guide to Get You Through High School and College Everything is in this book. A great resource for 15-25 year olds.
The New Speaking of Sex: What Your Children Need to Know and When They Need to Know It A starter book for parents.
On Your Mark, Get Set, Grow!: A "What's Happening to My Body?" Book for Younger Boys Madaras is the go-to author for young people on puberty.
It's So Amazing!: A Book about Eggs, Sperm, Birth, Babies, and Families All of Harris' books are gorgeous and full of accurate information.