i dont think theres any 'reason', its just how their legs go
i dont think anyone would force their legs to go like that, its just how they find it comfortable
it has nothing to do with looking feminine
when i was seeing an osteopath he had to continually tell me to uncross my legs (not like this, just lying flat with one across the other) and i kept doing it totally absent mindedly and out of habit, so i suppose these people do
i could not comfortably cross my legs twice, but some can