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4

Sex, Gender, and Sexuality

We humans can’t resist the urge to organize our world into distinct categories. We divide people, who may reflect an ethnic mix, into “Black,” “White,” “Asian,” or “Hispanic.” We eagerly identify people as either male or female. Before or at your birth, everyone wanted to know: “Is it a boy or a girl?” The answer described your sex, your biological status, defined by your genes and your anatomy.

For most people, those biological traits also help define their gender—their culture’s expectations about what it means to be male or female. But there are exceptions. Occasionally a person’s gender identity—their sense of being male or female—differs from their assigned sex. Writer Mark Morris (2015) reports that this is the case for his famous father, Jan Morris: “My father . . . is transgender. He always knew that he was, underneath, a girl, and my mother knew this when they married in 1949.” In 1973, his father had gender reassignment surgery and ever since has been “she” to family and friends. After the gender reassignment, British law (which forbade same-sex marriage) required his father and mother—who “continued to live together in a remarkably strong marital bond”—to divorce. Years later, when same-sex marriages finally became legal, they remarried.

More recently, the public has followed the journey of Caitlyn Jenner, the Olympic decathlon champion whose transition from Bruce Jenner made headlines. Cases like those of Morris and Jenner make us wonder: How do nature and nurture interact to form our unique gender identities? In this chapter, we’ll see what researchers tell us about how alike we are as males and females, and how and why we differ. We’ll gain insight from psychological science about the psychology and biology of sexual attraction and sexual intimacy. And, as part of the journey, we’ll see how evolutionary psychologists explain our sexuality.

Let’s start at the beginning. What is gender, and how does it develop?