The most resilient gender conventions in roleplaying games?

[Feddlefew]

I randomize gender whenever possible, as the need comes up.

I also have characters who don't fit into gender (or male or female) categories. Some are non-gender binary, some are hermaphrodites (both in the usual sense and sequential), and several important (non humanoid) NPCs use a radically different mating type system.

Edit:

In modern times, the gold digger is always a woman who targets rich older men.

In Victorian times, the gold digger is always male who targets spinster daughters of wealthy families, especially if they have no siblings.