The reason for this is that medical transition, primarily through the mechanism of hormone replacement therapy, actually changes some aspects of biological sex and the associated risk factors at a "nuts and bolts" level even though its not touching every single aspect of biological sex. It's not purely cosmetic, though that's a common misconception. Hormones ultimately control a lot about how human bodies express sex and the associated medical factors. In reality "biological sex" is composed of multiple sexually differentiated systems within the human biology that can theoretically operate somewhat independent of each other, and changing the dominate hormone in your body will flip or at least shove a lot of those systems towards the other end of the distribution. I guess a way to phrase this in developer terminology would be that "biological sex" is sometimes a leaky abstraction.
As a personal example: despite my birth sex, it would be a mistake for my doctor to ask that I routinely get regular breast cancer screenings in the same way it would be a mistake to ask a cis man to regularly screen himself for breast cancer. My risk of breast cancer is much lower than a cis woman's and comparable to a cis man's. But at the same time I have absolutely zero risk of prostate cancer, and it would also be a mistake to try and test for that based on any possible symptoms I'm having. An ideally perfect doctor would be able take my history and be cognizant of what risk factors of biological sex, exactly, which conditions were associated with, and then be able to map that onto my body to figure out what I'm at risk for. As you can probably imagine, this is very difficult to do. A lot of times what makes a condition linked to sex isn't actually understood in the first place.
anyway aside from language legerdemain, the word "sex" is also used to refer to what sex you're legally designated as, which is only loosely coupled to biology by now
It’s humane and polite not to describe people as abnormal, but being medically accurate I’d argue that humans are indeed binary sexed, and immutably so.
Then again, a lot of severe conditions that would often fall under the DSD umbrella are often overlooked until they become somehow important. For instance, complete androgen insensitivity, so zero functional testosterone in an XY individual, is often not diagnosed until you notice the lack of periods / cervix.
Calling it bimodal is a much more precise way to go about it that acknowledges we have two broad categories, with lots of exceptions and caveats.
Doesn't really matter, for this purpose.
> I’d argue that humans are indeed binary sexed, and immutably so.
Unless you defining terms such that the variations are not merely disorders but actually nonhuman, you are clearly wrong; human alignments of sex characteristics are non-binary though bimodal.
You either produce sperm, or ova - or neither (which if caused genetically is an abnormal variant).
“Producing the wrong gamete for one’s perceived gender doesn’t construct an additional sex, nor alter the definition of sex such that there are female sperm / male ova producers - this holds even if that perception has genetic as well as psycho-environmental causes” - in my opinion.
But .. we’re philosophical / political at this point .. which is the problem.
Or both, at least in theory, though true hermaphroditism with both ovulation and spermatogenesis, while theoretically possible and observed on other mammals has not, AFAIK, been conclusively shown in humans.
But, sure, you can redefine “sex” to be restricted to any one of a number of axes of sexual variation that exist in human and result in either a simple quaternary, trinary (or, if you try a little harder than you have, binary) distinction, but what is the point?
it's god of the gaps thinking, people are addicted to drawing clean lines around discrete categories as a vestige of modernism. taxonomy brain. we don't have good ways to say "there are two major clustering points, which most people are roughly close enough to one or the other to call them that, but there's enough overlap and so many dimensions that it makes drawing clean boundaries impossible"
I suspect as gene sequencing gets commoditized and personalized medicine actually becomes practical, we'll find a lot more cases where it makes sense to analyze people on the basis of their individual traits rather than what broad groups we can class them under