Our ideas around femininity and masculinity have significantly evolved in recent generations, but there is still lots of room for growth. Today’s guest argues that understanding the differences between genders — specifically, the ways in which girl brains differ from boy brains — can actually break down those gender stereotypes. Dr. Leonard Sax is a physician and psychologist, as well as the author of "Why Gender Matters: What Parents and Teachers Need to Know about the Emerging Science of Sex Differe