"Biological Sex" Isn't a Thing

It's just a transphobic dog whistle.

Image: Murderbot is neither male nor female; sex is a complex trait.

Over the last 5-10 years, as trans people have become more visible and more accepted, “biological sex” has become a new buzzword. Most people now recognize that trans people exist, and further recognize that when you talk about “women,” or "men" trans people are included in those groups. So, people who want to signal that they're excluding trans people from that group need to figure out other ways to get at it. “Biological women” and "biological men" are favorites because they sound scienc-y. It’s biology! It’s neutral fact languagespeak! Who could disagree?

But science-y isn’t science, and “biological sex” is a nonsense phrase which means nothing—except, again, that you want to exclude trans people.

“Biological Sex” Has No One, Clear Referent

When people refer to “biological sex” they think they’re talking about some single, clear biological truth that determines whether men are men and women are women (nonbinary people tend to get erased in these discussions.) Biological sex enthusiasts point to chromosomes, or genitals, and insist that one, or the other, or both can tell you for sure, no question, whether someone is male or female.

But as gender scholar Kim Elsesser explains at Forbes, this just isn’t the case. You can be a (cis) girl and have XY chromosomes. You can be a cis man and have XX chromosomes.

Genitals don’t work as a catch-all heuristic either. About 2% of babies are born with ambiguous genitals. Sometimes these babies are operated on to make them more gender conforming, despite ongoing intersex advocacy to end this practice.

If you are talking to an individual, online or in person, there’s no observable biological marker to tell you what their sex is. You’d have to do a chromosome test, and neither you nor the person you’re haranguing will necessarily know what the results are. Or you’d have to demand to look at their genitals—which is obviously offensive, and which in any case doesn’t necessarily tell you for sure much of anything.

When people insist that they are talking about “biological sex,” they’re really just using social cues to impose their own rule of thumb understanding of who is male and who is female, who is trans and who is cis. When someone says they are classifying people by “biological sex”, they’re not studying chromosome tests or genital exams anyway. They’re mostly just using stereotypical social notions of what men and women look like, and maybe looking at how people self-identify. Then they’re saying “biological sex!” to make it look like they’ve got some rigorous system. But they don’t.

A Complex Trait

And, again, they don’t because there’s no one marker of sex. Sex is a composite of numerous “complex traits,” according to Julia Serano, a biologist, trans activist, and gender theorist. In her book Excluded, she explains that complex traits are characteristics that “arise through an intricate interplay of countless biological, social, and environmental factors.” She goes on:

Because there are many different inputs that may influence our sexes, genders, and sexualities, there will always be a wide range of variation in potential outcomes, rather than one or a few discrete outcomes. Here is an example of how this might work: Given the fact that the majority of people are heterosexual, we might predict that certain sex-specific factors (e.g., sex chromosomes or hormones) might influence sexual orientation on some level. But there also might be other biological factors that are not sex-specific that are involved as well.

Sexuality—who you are attracted to—is no doubt influenced by (for example) your chromosomes, your genitals, the sex you were assigned at birth, your hormones, your brain chemistry. But it’s also often influenced by your experiences, by social pressures, by developmental experiences. There are so many factors involved that you can’t point to any one thing and say, “this biological on/off switch for sure is the thing that has made me be heterosexual/homosexual/bisexual.” That’s not how complex traits work.

Sex is a complex trait too. And again, that means that there’s no one factor that determines what sex you are. And since there are so many different factors, biological and social, no one is in a position to categorize you or say for sure who you are. The person best positioned to determine your gender is not the doctor with a chromosome test, not the doctor looking at your genitals, not some dope online demanding easy classifications. The person best positioned to know what gender you are is you.

This is also, as an aside, why the sex/gender distinction is largely useless as a way of classifying human beings. Sometimes people will use “sex” to mean biological expression and gender to mean “social expressions”. But as we’ve seen, sex is a complex trait; it includes biological and social and environmental factors which affect each other and can’t be teased apart from each other. It makes no sense to say, “my sex is x, but my gender is y” as if biological and social can be parsed out and grouped. Sex and gender are just two different ways of saying the same thing; analytically, separating them confuses as much as it clarifies.

Trans People’s Sex Is Biological

Again, "biological sex" doesn't mean much of anything. But to the extent that everyone's sex has biological components—well, if that's true of cis people, it's true of trans people as well.

Most people at this point understand that sexuality is in large part biology; there's no one biological factor that makes someone straight or gay, but who we are sexually attracted to is still (at least in part) rooted in our brains, our hormones, our genes, or some combination thereof.

That's true for trans people too. Some trans people know that they're trans almost as soon as they know anything, which suggests a strong biological component to their identity. And all trans people face enormous social pressure to not be the sex they are. How can trans people's identities be purely social when they are the people most defying social norms about gender? It's cis people who go along with the social designation of their gender, which means that if anyone's gender is "social" as opposed to "biological," it's cis people.

But (as I've said over and over) the fact is that no one, cis or trans, has an exclusively social sex or an exclusively biological sex. Everyone's sex is a mishmash of a whole range of factors. And no one benefits from having this sex or gender policed or dismissed on the basis of someone's confused understanding of "science."

The most human thing about humans is that we're not just "biological." Most of being human happens in the space where we interact and live and talk to other people. Reducing someone to their genitals, or their chromosomes, is a way to deny them their personhood. Which means that when trans identities are accepted, everyone, trans and cis, is more human.