Male? Female? The distinction is not always clear. Exploring the scientific evidence for the biological origins of sexual orientation and gender identity must continue to both enhance patient care and fight discrimination. People often are unaware of the biological complexity of sex and gender, says Eric Vilain, MD (RES ’98, FEL ’99), PhD, director of the Center for Gender-Based Biology at UCLA, where he studies the genetics of sexual development and sex differences. “People tend to define sex in a binary way—either wholly male or wholly female—based on physical appearance or by which sex chromosomes an individual carries. But while sex and gender may seem dichotomous, there are in reality many intermediates.”
Dr. Vilain says that understanding this complexity is critical, as misperceptions affect the health and civil liberties of those who fall outside perceived societal norms. “Society has categorical views on what should define sex and gender, but the biological reality is just not there to support that,” he says.