But it seems like the intended purpose is for avatars, though – if I recall, the original question is "pick the sex of your avatar," not "how do you identify." I don't know how you could keep the avatars in place while also offering "prefer not to say" (my personal preference) and "other" categories. The system itself might be inherently flawed.
Their statistics could easily include an "other" or "prefer not to say" option, and would make it more accurate.
But it seems like the intended purpose is for avatars, though – if I recall, the original question is "pick the sex of your avatar," not "how do you identify." I don't know how you could keep the avatars in place while also offering "prefer not to say" (my personal preference) and "other" categories. The system itself might be inherently flawed.