“In the rare cases where actual psychological differences exist, they cannot be attributed to innate neurology alone. Everything in the brain is a combination of nature and nurture. Culture comes into play, which affects behavior, which then affects the brain. From birth (and even in the womb), a baby is labeled as a girl or boy and treated a certain way as a result. For example, a 2005 study of 386 birth announcements in Canadian newspapers showed that parents tend to say they’re “proud” when it’s a boy and “happy” when it’s a girl. Anne Fausto-Sterling, a biologist at Brown University, has shown that mothers talk to infant girls more than infant boys. This could partly explain why girls tend to have better language skills later on. “Some differences end up fairly entrenched in adult human beings,” Fausto-Sterling says. “But that doesn’t mean that you were born that way or that you were born destined to be that way.””