[eksith]

The solution is already available by the very same folks who would just as easily think nothing of presenting that "female | male | other/it's complicated | prefer not to answer" field though.

In lieu of questioning who the user is, may I suggest see what the user does instead? Behavior, in the end, is the real key to unlocking demographic potential. What purchases are made, what items were clicked on, where they had browsed and what titles on pages attracted them on the site can tell far more than a simple field.

This, of course, takes time and testing plus accumulation of data. But since a fair number of HN users also like to exalt the status of "Big Data", there's a more productive use for it.

Don't try to finagle who the user is or isn't. Just find out what they want.