The right to mis-define oneself

[Longhorn]

Okay, I'll concede that.  In my defense, you'll see that a couple pages back, I directly stated that gender issues are more complex, as gender identity is largely psychological.  Race, however, is normally used to refer to the geographic and/or genetic background of a person.  That being said, I think a person with a complex gender identity should be described multi-axially: genetics, physical makeup, and psychological identification.  Jenner, for example, was clearly born male, is currently mixed male/female anatomically (if you accept silicone breasts as "real"), and clearly is not a typical male psychologically.  In a sense, you could say he's all of male, female, both and neither.

I'd say she's a female in all ways except for the strictly biological sense-physical appearance and genetics, but even her brain is structured differently to a male

I think trying to squeeze the many gender-definining characteristics into a single label is the source of most of the sour grapes about Jenner and other transgender people. But my point of contention isn't what someone identifies as: it's whether someone is allowed to impose their view or definition of a word on other members of the society. Does the fact that Caitlyn wants to be seen as a woman automatically mean that everyone else has to pretend Caitlyn is as much a woman as, say, your mom?

What characteristics are those? As I said, it's nothing to do with stereotypes, gender roles or interests

Define 'has to'. I really don't know what you mean. She is female. She isn't 'imposing' anything on anybody. You're not forced to refer to her as female. She's simply being honest with people about who she is, don't you think she has the right to do that?

Also, as you can read in the link I gave you, gender dysphoria means extreme discomfort and using the wrong pronouns is pretty hurtful. It's not some sort of obligation, just not being an asshole.