They don't even distinguish between non-binary & binary & they are like polar opposites in many ways. There is also a massive chasm of differences between the homosexual ones & the heterosexual ones. Most "trans kids" are gay, most trans adults are heterosexual (often shifting into bisexuality when they transition, even without hormones). The brain differences are only in the homosexual ones, because they are the same brain differences all homosexuals have compared to heterosexuals.

"Transgender" isn't an identity, it's a phase that predominantly affects gay children, which is why promoting the idea of trans children is just makeshift conversion therapy. Up to 95% desist if left to their own devices, but when they are put on puberty blockers the desistance rate drops to just 2%! Cross-gender self-identification is the phase, transition is the name of the conversion therapy method.

Here is the source for the 25% of serial killers cross-dressing, so a quarter of all novels could feature them & still wouldn't be demonstration, just accurate representation:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.457.3731&rep=rep1&type=pdf