You get trans women who are masculine and trans men who are feminine. I've known a trans woman who dresses so masculine, people assume she's a trans man who hasn't transitioned yet. I've known several trans men who wear skirts regularly.

But they're 100% in their genders.

It's an innate sense of self. You just know. I can't tell you what it is, honestly it doesn't make a damn bit of sense to me. I know that I'm neither a man nor a woman. I've tried being a woman, I've tried being a man, both were like wearing ill fitting shoes. Uncomfortable and, for long periods of time, painful.

It's just an innate sense of self.

I've seen a few people speculate that most people DON'T have this sense, that most people honestly just go by what they're told. So most men would have been fine if they'd been born women, and vice versa, but because they were assigned male they roll with that. So a lot of the confusion about trans people is from (in theory) most people not having that innate sense.

That's just a theory. Without a better grasp of what gender actually IS, it's impossible to test. How do you tell the difference between a cis man who has an innate sense of being a man, and a cis man who was told he's a man and is okay with it? You really can't.