I have little doubt that we have all heard the line that transphobes use, that your gender is what you're born with, you can't change it, etc, and needless to say this is stupid, almost as stupid as the time I saw someone on reddit trying to convince someone diagnosed with NPD they didn't actually have it (the stigma surrounding that condition is absurd). But while I'm assured most of us know that this is wrong, I still think it's important to know why, and what better way to do this than by using the very same 'basic biology' these people try to uphold?
To begin with, it's quite easy to see that the very concepts of 'male' and 'female are vague when you get into the specifics. As I have mentioned several times in the past, 'maleness' as we usually think of it is not in fact determined by the entire y chromosome, but by only a segment of it. If that segment is lost, as it sometimes is, the person in question develops as female but is chromosomally 'male', by the definitions of transphobes. So are they actually male or not? Either way, their criteria are completely broken down. And this problem isn't just limited to the Y chromosome; what about XXY men? They bear some female secondary sexual characteristics, but they are undoubtedly recognizably developmentally male. And X, XXX, and XXX+ women do exist. What about them? Should XYY men be banned from sports as well due to their supposed heightened testosterone?
To make matters more complicated, development of sexual characteristics is more complicated than just one gene. If anything downstream malfunctions, someone can end up with both male and female reproductive structures, also known as intersex people. What about them? Are they supposed to play male sports half the time and female sports the other half?
Even ignoring all this, the very conclusion that the existence of trans people is 'unscientific' is false. The consensus in the scientific community is that sex and gender are indeed separate, and can be misaligned for an individual. If they're willing to deny what actual scientists are saying for their own ideology, they're free to do that, but they have no excuse to pretend to uphold science. How do I know what scientists agree on? My anatomy and physiology textbook. From 2006.
An entire decade before the whole wokemongering bullshit started. It's not as if the authors are particularly progressive either; several other textbooks I own from the early 2000s to a few years back agree on this.
I think it's quite clear that anything transphobes say isn't based in fact, but only their own delusions. They can't deny that they don't give a shit about biology at all, which is perfectly fine to me. However, they shouldn't go around masquerading as triumphant 'experts' when they don't understand what they're trying to use as a cudgel. The sad thing is, many uninformed people will see their rhetoric online and fall for their bad faith arguments, and I think it's the responsibility of those who know better to not only tell them not only that they are wrong, but also why they are wrong.
I apologize for the terrible structure and awkward phrasing.