There are people who don't identify with a gender and aren't going to be included in any list of them you'll be able to come up with.
Don't bother saying "What if I check between their legs?" or anything like that, because gender and sex are two different things that are merely strongly correlated in most people.
I think it's a stretch to say that physiology plays no role in defining gender. Say the gender drop-down is being used on WebMD to present biologically-relevant information for someone ... then the gender drop-down helps to identify what physiological issues the user's body is likely to experience.
> the gender drop-down helps to identify what physiological issues
Web sites that need to know how a person is physically constructed as opposed to socially constructed are going to be rare.
But even then, the physiology is not always always binary: "1 percent of live births exhibit some degree of sexual ambiguity.Between 0.1% and 0.2% of live births are ambiguous enough to become the subject of specialist medical attention" - http://en.wikipedia.org/wiki/Intersex#Prevalence
Well what if someone is trans gendered? What about a trans women who hasn't changed her birth cert, but has gotten a sex reassignment surgery (i.e. has a vagina now, no testicles) and has been taking female hormones for years? What should they put down? They are probably more likely to have female medical problems than male.
Then they should choose whatever is most applicable to their special-case. And really they're unlikely to have female problems given that while body parts are shaped into something resembling the other gender, they don't truly have functional versions of these body parts in the traditional sense. A man that becomes a woman doesn't ovulate or cannot become pregnant for instance.
Look, EVERY website is built based on some assumptions. Sometimes it's that people comprehend a certain language. Sometimes it's that they're using a browser with support for images and they're not using LYNX. The general assumption of most websites is that their user hasn't changed their gender ... and while I'm sure there's some equal-rights group that would disagree with me, I think that's a fair assumption. I'd also bet that for the vast majority of sites that request gender information, that input is unlikely to ever have an impact on the user's experience on that site.
If a user has transformed their identity, then I think they've also taken on the responsibility of figuring out how that new identity will navigate the real-world. That means a woman that identifies as a man can enter "Male" in a gender drop-down if that's how they choose to self-identify, but unless they've had a surgical procedure to change their physiology, then they're still going to need to operate their body like any other woman would. If they're in a pharmacy, that means buying feminine products to maintain their body. If they're on WebMD, that may mean declaring themselves as a woman to get relevant content. If they're on a dating site, maybe it makes sense to declare themselves as a man ... much to the potential future chagrin of their date.
Yep, lots of things are based on assumptions, but one should also look at your audience. E.g. an endocrinologist (hormone doctor) will probably see a large percentage of trans patients.
> I think it's a stretch to say that physiology plays no role in defining gender.
I never said that was true in all cases. In fact, I said it was strongly correlated with gender in most cases. However, it isn't an absolute determinant, especially if you equate 'sex' with 'genitalia'.
The detection may not be more sophisticated, but the UX is a bit better now. Now it says "Our automated system will not approve this name. If you believe this is an error, please contact us." The "contact us" links to https://www.facebook.com/help/?faq=212848065405122. In that FAQ, it explains that you need to use your real name, and leads to another link where you can appeal the automated decision: http://www.facebook.com/help/contact/?id=237843336274237. You have to upload a government-issued ID to get the account.
