I honestly think discussing possible options to have listed is a fruitless exercise considering there could be [url=http://www.telegraph.co.uk/technology/facebook/10930654/Facebooks-71-gender-options-come-to-UK-users.html]71 different gender options[/url] that we would have to list if we we're to go down this road of selection.

Easiest option would be "custom" and we either list every option or we allow custom input like "attack helicopter".