Photo of a drag king holding a rainbow umbrella during a pride parade. Photo by IowaPipe, Flickr CC
According to a recent memo, the U.S. Department of Health and Human Services is seeking to establish a legal definition of sex and gender based on “a biological basis that is clear, grounded in science, objective and administrable.” However, social and biological scientists agree that — based on their scientific understanding — gender and sex are not solely biological, and sex and gender are not the same thing. Sex is a category used to describe a culmination of biological and genetic components, including chromosomes, hormones, and physical anatomy. Gender, on the other hand, may or may not be linked to biological traits. Gender refers to a cultural identity, one that has social weight in the world, with particular meanings attached to it. Gender involves social norms, attitudes, and expressions.
Neither sex nor gender are binaries, meaning there are not just two categories — female or male, women or men — and they are not fixed or static. They can and do change over individuals’ lifetimes. U.S. society is increasingly more likely to accept that gender is more of a spectrum than a binary. We’re hearing more about transgender individuals in the media, but transgender is only one gender identity that challenges a binary view of gender. Others include, but are not limited to, gender nonconforming, gender fluid, and gender queer.
Just as gender is not a binary, neither is sex. The biological components of sex do not always align solely with “male” or “female.”  An individual may have XY chromosomes and an outward female appearance, including breasts and a vagina. Another might have XX chromosomes and high levels of testosterone. Yet another might have genitalia that appear to be neither male or female (too long to be a clitoris, too short to be a penis). These individuals fall into a category called “intersex.” While it’s hard to know how many individuals are intersex (some don’t even know themselves), a commonly reported statistic is 1 in 1500 to 2000 American births.
Nevertheless, U.S. society remains deeply invested in two categories of sex and gender. In fact, most of society is organized around these ideas. In other words, gender is an institutionalized system. And during our everyday lives we constantly categorize people based on their appearance and behavioral cues — gender is a system of categorization we use to understand our social world. People who challenge gender or sex binaries thus can face serious consequences, including discrimination and violence.

No doubt, the recent controversy in the Department of Health and Human Services isn’t the first time we’ve grappled with contested definitions of gender and sex in our political history — and it certainly won’t be the last.