I don't think someone can choose race just as they can't choose gender identity or sexuality. Science shows that there can be a disconnect between sexuality and gender. Science doesn't justify the same disconnect on race for me.
"science" hasn't shown that there can be a disconnect between sex (i think you mean sex, not sexuality), at least no science that you have mentioned in this thread. the fact that males and females have distinct brain characters does not imply that a disconnect between how someone perceives their own gender and their biological sex exist. all it does is suggest a hypothesis (again, i insert the caveat i restrict my comments to the scientific observations that you have presented in this thread, since i am not well versed on the subject matter) that might explain the origin of empirical observations of such disconnections.
your comment on disconnects in racial identity makes little sense unless you are arguing that dolezal is lying about her preferred racial identity.
As far as this particular case goes, Dolezal has consistently lied about her upbringing which to me shows that she doesn't really believe it is something that you can choose.
one of the things that makes this case interesting to me is that i perceive dolezal to be sincere in her preference to be considered black. i do not perceive her to be doing so for ulterior motives, or to be misrepresenting that preference. i would consider her lies about her parentage to be her realizing that society would not accept her preference for being black if simultaneously confronted with her european ancestry, and inventing a story that allow society's perception of her to correspond to her own preference, rather than something that she needed to invent in order for her to allow herself to believe she is black, which i believe is what you are suggesting.