Something that I think will stretch everyone's boundaries.
"Brain Sex" theory says the following -
1. The human brain is not homogenous
2. Some bits are sexually dimorphic - though they may also conform to neither stereotype
3. Some of the sexual dimorphism is due to current hormone levels
4. Some of the sexual dimorphism is set before birth, and will develop within narrow bounds later
5. Sexual dimorphism is anything but binary
6. Certain parts of the brain determine gender identity (by organisation-activation)
7. Certain parts of the brain determine body map, in particular, appropriate genitalia
8. Certain parts of the brain determine sexual orientation - gynephillic, androphillic, both, neither.
9. Certain parts of the brain determine sense of smell, dichotic hearing etc
10. Certain parts of the brain determine play patterns as children
11. Certain parts of the brain determine interests and talents as adults
Now for some crucial bits
13. If some sexually dimorphic parts of the body are masculinised, usually most other bits are too to some degree. This applies to the body as a whole, but also the different parts of the brain. But, and this cannot be emphasised too highly, there are degrees, correlation is statistical not absolute, it's usual for some parts to be closer to a male rather than female stereotype, and other parts the reverse. There's no such thing as a "male brain" or "female brain". "Male" and "Female" don't refer to Platonic Ideals, just patterns found more commonly in one sex or the other.
What this means - some predictions.
Lots of men where everything lines up - male gender identity, male genitalia, gynephilia, male play patterns when young, "typically masculine interests" as adults, typically male senses of smell and hearing, and so on, with female equivalents.
Non-op trans women.
Girls with CAH who show male-typical play patterns and later often gynephillia (but female gender identity)
Boys who show female-typical play patterns and later often androphilia (but male gender identity)
And men like this. Male gender identity, usually androphilia, and non-masculine genital body map. "Nullos".