haibane
paul in order to win the respect of the fremen and become the emperor you have to ride the biggest worm in the land. you have to change your name. drink this blue stuff for girls. have you been practicing the voice
Paul should've been trans. Hell maybe intersex too. No I have not read the books 
If I'm gonna be a stickler about the lore, that XY chromosome combo seems to be a necessity for other memory of both sexes. Past that nothing says Paul can't be trans, intersex, etc.. Granted, by book 3 I think it's a little more loose on that requirement. This is also a book that has bioengineering and cybernetics. Still, Frank being an SF dude in the 70's meant he was ahead of his time in some areas, them wildly homophobic in others.
In short the powers the Space Nuns wield is regarded as too dangerous for men to handle, both being lethal to men who try to use it, as well as too dangerous if a man should somehow survive the training process.
If I'm gonna be a stickler about the lore, that XY chromosome combo seems to be a necessity
Have her be a chimera who ate her twin sister in the womb.
