What is it that makes a person a boy or a girl? From our cradles to our graves, a pair of letters, either XX or XY, will define much of our lives. "It's a girl!" or "It's a boy!" will be the first label applied to us, the first thing said about who we are as an individual. For every person in every society, gender has a fundamental affect on what w...

Making Girls and Boys: Inside the Science of Sex