The concept of “biological sex” is bullshit. When talking about trans people and the sex they were assigned at birth, the terms “biologically female” and “biologically male” are often thrown around without any critical interrogation into their meaning. They’re a fallback for a lot of people who are aware that saying “born female/male” is reductionist, but who haven’t yet done the work to find more accurate terminology. (The terminology I use and recommend is “assigned male/female at birth”). For a variety of reasons, “biological sex” is a faulty concept, rife with scientific inaccuracies, that subtly undermines and invalidates trans identity. Like a pointillist painting, the closer you examine the concept, the more you realize it’s just a cluster of meaningless points of observation, designed to trick you into seeing a complete picture that was never really there in the first place.

A couple weeks ago I saw a new doctor and got to experience (for the umpteenth time) the joy of trying to explain my body to a medical professional. It’s a mutually confusing experience. Confusing for him because the terms he used to try to render my body legible were both scientifically inaccurate and disrespectful; confusing for me because I don’t think he needed to know what kind of genitals I have in order to treat my acid reflux. I have very little interest in making my body legible to cis people, but I was interested in getting my point across so we could move on.

He asked to see my top surgery scars. As far as I’m aware, that had fuckall to do with gastroenterology. Then he asked if I was biologically female, and I told him no — but I was assigned female at birth. He struggled to understand the difference. The conversation stretched out more than five minutes, then more than ten. I was waiting to be treated for my actual concerns; he was more worried about deciphering the specific conditions of my “sex,” whatever he assumed that to mean. The essay that follows is a more polished and thorough (and occasionally more profane) version of what I told him.

The concept of “biological sex” is bullshit. When talking about trans people and the sex they were assigned at birth, the terms “biologically female” and “biologically male” are often thrown around without any critical interrogation into their meaning. They’re a fallback for a lot of people who are aware that saying “born female/male” is reductionist, but who haven’t yet done the work to find more accurate terminology. (The terminology I use and recommend is “assigned male/female at birth”). For a variety of reasons, “biological sex” is a faulty concept, rife with scientific inaccuracies, that subtly undermines and invalidates trans identity. Like a pointillist painting, the closer you examine the concept, the more you realize it’s just a cluster of meaningless points of observation, designed to trick you into seeing a complete picture that was never really there in the first place.

Western society is governed heavily by science. The so-called “Enlightenment” period positioned empirical scientific observation as the sole legitimate way of knowing. Long gone were the days of the hypothetically theorized four bodily humors; now, science could be — and had to be — carefully observed through the senses, and carefully recorded for future study. Positivism says that if we are confused, scientific research is the sole way to determine the truth. If we find that our past research is wrong, we can simply do new and better research find the right answer. Nearly all our knowledge about how our bodies grow, move, work, reproduce, and live stems from the field of biology. Biology — and empirical scientific research in general — are held up as the source of truth and proof in the world.

I provide this context to clarify why the term “biological sex” is invalidating. If the field of biology is the source of all our knowledge about the human body and its workings — if biological science is the bottom-line “truth” of the body — then telling a transgender woman that she’s “biologically male” insinuates that even though she identifies as a woman, science proves at the end of the day that she’s “really” male. I hope I don’t have to explain why that’s disrespectful.

Beyond that, it’s just incorrect. If you’re cis, ask yourself this: what does “biological sex” really refer to? Genitals? Chromosomes? Hormones? Secondary sex characteristics like facial hair and fat distribution? Or are you starting to realize it’s just a vaguely defined concept with no definite grounding in the physical factors it claims to characterize?

Very few things about the human body are truly binary, and sex is one of these factors. The existence of countless intersex people presents evidence that there is natural variation within the human species beyond what is covered by binary male and female sexes. Some people are born with genitals that do not meet the strict criteria for a “typical” penis or vagina. Some people are born with chromosomes other than XX or XY. These people may not identify as trans; sometimes, they do not know about these parts of their body in the first place because surgery is often carried out on babies to make their genitals conform to societal norms with little regard for children’s health or consent. Before I begin to address gender identity as separate from sex, the concept of an easily categorizable binary sex begins to fall apart.

The concept is also wildly mismatched with the realities of many trans people’s bodies. For trans people who choose to medically transition via hormone replacement therapy, their bodies quickly leave the realm of what is easily categorizable by binary sex. Their hormones and secondary sex characteristics — that is, the vast majority of their sex-related characteristics, everything except their genitals — will no longer be definable as “biologically” the sex they were assigned at birth.

Like, I’ve been taking testosterone injections for six years. I am rarely not perceived as male; pretty much all the visual signs people use to recognize gender read “male” for me. Judging by hormones and secondary sex characteristics, my body works quite similarly to the bodies of cis men. My original birth certificate reads “female,” but even that has been changed since I legally changed my name. I have very little connection to any tangible aspects of “female-ness.” When people ask me what I am “biologically,” what are they really asking?

Due to the complexities of sex-at-birth and the changes resulting from medical transition, the term “biological sex” cannot accurately describe anything except the genitals of people who haven’t gotten bottom surgery. Thus, “biological sex” is little more than a weak euphemism for penis or vagina. If you’re asking about someone’s genitals, say what you mean, and own the fact that you’re asking an extremely invasive and bizarre question that you probably don’t need the answer to. Stop cloaking your discomfort in euphemisms like “biological sex.” If you’re a grown adult who can’t bring yourself to say “penis” or “vagina,” then frankly, it’s not my sex you need to be worried about.