The reason I like "people can change genders multiple times per day" is not because it suggests your implementation of gender should support that, but rather th

The reason I like "people can change genders multiple times per day" is not because it suggests your implementation of gender should support that, but rather that you should not try to implement gender at all. One of the main messages from these is to stop mindlessly asking for "Last Name" or "Gender" when your system has no need for that information to do its job. Get your system to do its main job, and if there is still a free variable (e.g. what gender do we use for verbs when talking about you in German?) then ask only that, specifically. The people who change genders multiple times per day are doing it because they see their different genders as applying to different situations, and you should be clear about what situations you're asking about. "Eddie Izzard, why do you wear women's clothes?" Eddie Izzard: "I don't. These are my clothes. I bought them."