"what is the third gender" your deliberate misunderstanding and simplification of the issue is just bad faith debate. you're proving us that fractions are "syndromes" by using only integers. this is just a display of ignorance and bigotry, it doesn't really paint you as smart as you're trying to appear

Arguments mate, or you are just wasting our time.

So far you've only voiced your transphobic opinion, that's not how a good dialog is started.

Arguing with you is a waste of time.

If you're going to do a binary, X and Y chromosome doesn't hold up due to the presence of functional XX males from an SRY gene. Its speculated most Y chromosomes started as X chromosomes in animals that have that dichotomy.

In fact a functional or non functional SRY gene is a better determinant for biological sex.

The fact is though that testerone and SRY receptors have relatively high variability and trying to socially stress people into a group of traits will create a feedback loop that is opposed to more natural courses of evolution.

Its likely trans people - of whom there are records of going back to time immemorial - are likely an evolutionary adaptation and serve some evolutionary function to society we may not yet understand

Since gender is socially constructed (male norms, female norms, male jobs, female jobs) the presence of trans people in society that not only understand both sets of roles but can navigate them is probably an advantage over societies where those roles are less fluid and more strict.

There's a case to be made that the more strict gender roles become, the more evolutionary pressure there is to create trans people.

You haven't read anything about this. It's very clear. The first thing you learn is that sex and gender are different. Sex is biology. Gender is identity.

The second thing you learn is that sex is not binary. (And gender, being a social construct, certainly is not set in stone.) Genes may be XX, but maybe some other factor may be preventing that gene from expressing fully or even at all. This can lead to highly androgynous folks or folks with odd genital configurations. It takes genes, gene expression, and hormones for a human to express characteristics of some sex. Not all three of these are perfectly aligned. You can argue that genes control all of it, but that doesn't stand. Genes can conflict, and environmental factors can affect things.

I learned all that and more in just twenty minutes of reading. Please, go do some homework. Start with "what is the difference between sex and gender," then let the rabbit hole take you down. At least, that's the path that helped me learn a bunch of this stuff.

And regarding Dunning-Kruger, the key point is confidence. That said, I'll caveat all the above I've said with this is just stuff that I've read from sources that I trust, which I can corroborate with my existing knowledge of genetics and broader biology. I'm not an expert. I can be proven wrong. Most of this is definitions and quite simple stuff, so my confidence is high but still shakeable.

Normally, I'm a stickler about answering asked questions, but your questions seem to be based on a misunderstanding of definitions. Once you get that sorted out, we can try again and maybe learn something together