Is there a scientific answer to this? I believe the answer is only a “qualified” answer. Like I mentioned - any 100% answer cannot be correct. Even “common sense” answers of “I know what a biological woman is” are wrong in several circumstances. I’m not a researcher, only a layperson with a decent amount of of biochem and related coursework under my belt. I get the subtle comment about me not knowing enough to confirm or deny it. I’ll say sure to that one. I’m not an expert.

I question why there’s a debate at all. There are really only 2 “platforms” of concern apparently from all political discourse I’ve read: 1) Bathroom usage and 2) Sports. I would like to change your comment this is just what the scientific method has shown to add my own part that you yourself captured: in approximately half of the population (statisticians will forgive me for “half” when it’s a variant ratio over time of women to men (I think 105% of men born to women born).

But let’s take that half the population and pull a number out of the hat to say 99.99% of all people born have an obvious sex assignable at birth (via whatever means). OK, but that leaves 1 in 10,000 as the outlier to which the UK is now attempting to apply a law. Something close to ~370K babies are born daily. That’s 37 people per day world-wide and my ballpark percentage is egregiously conservative. 13,500 people in this ambigous state world-wide per year.

These are people, they have rights and deserve to live life. They should have access to toilets and education. It’s certainly expected in Western societies - you would expect NO LESS for the 99.99% who are clearly identifyable by external/internal/microscopic means. So ultimately all of this is just used to marginalized an already tiny population of people before we even consider gender role, brain phenotypes, hormone production / lack of production, etc. I think it’s fair to say "some people are born different, many of them don’t realize what is “different” until they reach puberty and start to notice “hey, I’m not like the other girls/boys”, perhaps even coming to terms with a stark realization that terrifies them “well shit, I guess I’m trans”. If you think that Trans people make certain Cis people feel uncomfortable, put yourself in the Trans person’s shoes! I doubt any one comes to that internal understanding lightly.

The ONLY reason to treat trans people or even “debate” what sex they are (without them getting any say in that!) is to marginalize them. The VAST VAST majority of humanity does not fall into this situation, and I’d argue are almost to exclusion not impacted by it personally. The notion may make them feel uncomfortable. Perhaps even physically concerned in some cases. But what’s to debate? That a trans woman should not use a female bathroom stall? Lesbians walk girls locker rooms the world over - should they not be able to go to the bathroom with other “biological” women? By the way, even that is easily solveable with lockable individual/family toilets/showers

So, I guess after this long diatribe (and thanks for sticking with me here) I would say, it’s almost completely irrelevent what science “shows” here as any “definitive” answer requires assumptions or exclusion of a small portion of the population to be definitive and the only purpose of the “debate” is to shunt an already fragile population into further inhumanity.

By the way, if science somehow today immeidately said X criteria is definitively a biological female, to what end would that information be any more useful than our passionless view of dogs or other animals? The answer? To exlude anyone not X. It’s the inevitable and only conclusion.

Ninja edit: “answer” to “conclusion” in last sentence