I know a few people who are non gender specific.
One is a person born male who dresses female, although they have no intention of having a sex change, they just live as someone called Suzi-Dan Jones. Not the real name.
Another is Alex dressed as male some days and then female for months on end, then male again. alex has changed names too more times than I can remember.
And finally I know Sam, who's birth gender I genuinely dont know nor does it matter to any of us, it just seems very natural for Sam to be gender neutral.