Thank you @mrfuji3, @Silver/ and @The_Red_Queen for your answers!
Putting this in spoiler since it's more off-topic :
BG3 have set personalities/goals/etc and are more tied into the entire game.
That's the thing, the way I see it, those things are not related to or defined by genders.
But I hear you guys, I see your points 🙂
All I'll say is : it's complicated (I think that's a fair statement 😄) and I personally will leave it there.
it also weighs against that option by the increased amount of work. 5+ origin companions, for BOTH situations where they're a companion and the PC, accounting for their personalities & interactions with NPCs, throughout the entire game...it all adds up.
That, yes, I fully agree 😅
But, like stated by OP, this thread is mostly theoretical ; not so much to expect this to be in the game.
"What if' questions can sometimes be the start of fun/harmless conversations that won't lead to anything concrete *thinking of conversations with a certain elven vampire*.