Peers are the gender police. Theres very high rates of segregation by sex in the playground, and it is a result of childrens own preference. There are a number of gender studies that show you can enforce gender integration by rewarding children who play with opposite sex peers, and then as soon as that reinforcement is removed, they go back to their own way of doing things. Sheri Berenbaum, professor of psychology
Sheri Berenbaum led a thought-provoking discussion about the often-debated topic of gender differences. An inquisitive crowd kept Berenbaum on her toes as she answered questions concerning whether gender differences are innate or learned. Drawing on over 15 years of research on congenital gender disorders—and using props such as Legos and make-up kits to illustrate her points—Berenbaum challenged the audience to "think outside the box" about the mix of social and biological factors that make us male or female.