mostly the main "body type" selection. athletic/ petite/ muscular/ etc. i thought maybe you were picking the same thing every time, but it seems that is not the case.
you hit the same class that i used, and still were affected.
oh, and one thing to keep in mind is that in almost every camera angle/ animation, the balls kind of cover the vagina, but it is there. though, if you do not have the trait, i think you don't have the part on the keeper's model.