I don't think that Quina's gender is that much of a mystery to be honest...
I mean i know Quina is a man and i can proove it...
The "Extension" item that can be eqipped as an accessory can only be equipped by women...
If you try and make Quinna equip this item, you can see he can't...
This must mean only one thing...
Quina is a MAN!!
If you don't like my theory or you would like to share your own ideas on Quina's gender then i would really like to hear from you. Thanx.

Lucrecia Valentine xXx