I think I've fallen into a trap. This post is an attempt to get out of the trap.
I've given away too much thought share. Only physical gender is provable, because only physical gender exists. This heterosexual/homosexual stuff is just fantasy, from a culture that long ago divorced marriage from procreation and instead, at the insistence of the greeting card companies who made lots of money off of it, made it about romantic eros.
Romance is fine when kept in its place. It's a great way to bind parents together for life. Women seem to crave it. But it is not the end-all-be-all of love, let alone human existence. It is possible to survive with no romance at all. It's possible to live without any physical human contact at all.
Physical gender is required for pro-creation. But this romance stuff? All hooey.