Well... right off the top, so to speak, is the problem that many of us don't necessarily fall neatly into the male / female binary. So you'd have to figure out how to identify all of those folks. I suppose the options could be: male, female & non-binary. But I don't know how individuals who would potentially fall into a "non-binary" category would feel about that. Plus you have some folks with multiple personalities some of which are male & some female... and individuals who are bi-gender. Personally I think this could open a can of worms that is better left sealed.