Child, this is called sexuality.

Author: People's Initial Magazine
Publisher:
Publish Date: 2000-07-01
Features: When you open this book, dozens of "authentic" life stories and popular science short articles will tell you that "sex" has always accompanied you through childhood, maturity, and old age. A lack of sexual knowledge will be a great shortcoming in life. So, don't let yourself and your child regret it forever. Read this book!