Let me preface this by saying I am not a social justice warrior, and am a very normal person with what I think are very normal beliefs. There is a difference between gender and sex. There are exactly 2 biological sexes, male and female (of course there are people who are intersex, meaning they were born with a combination of male and female sex organs, but I don't really count that as a third sex because it's simply a combination of the two, though some will.) Gender is what a person personally identifies as, and this can differ from their biological sex. There are too many to list here, but gender is a matter of personal identity, much like a sexual preference is or a religion can be. Think of it like this: if you were born into a Christian family, and you went to church every Sunday and did all the things a good Christian does, but you never felt comfortable in the ideology, or values, or whatever the case may be, you could convert. You could convert to Judaism, Islam, Buddhism, or even drop religion altogether and be an atheist. This isn't a matter of wanting to be a "special snowflake", they're just what feels right and comfortable for the individual. Let me say again, I am not being a social justice warrior. I am a straight male that has never questioned my sexuality or my gender alignment, but I feel that a lot of the hate on this kind of thing is brought about by a lack of knowledge or by sensationalizing the issue to the point of annoyance.