Responses

Despite your answer being damn funny haha (≧∀≦)
It's not unreasonable... He was kept in isolation, with pretty much only his mother being there for him and no education on top of it.
If he never got taught the difference of woman and man. Then he only saw them with clothes and the outer difference then is mostly about how they cloth and probably truly doesn't know... ( ̄∇ ̄")
I'm still very confused about the dinamics in bed... and how does Yu 'er think that Xuan Xiao doesn't know he's a dude ┑( ̄Д  ̄)┍