As far as I know, there are no specifically identified genes or gene sequences that dictate the facial features of a human being. And yet we see humans who's facial features resemble their parents to a remarkable degree, all the time. We also see children who's facial features do not resemble their parents, all the time. And since facial features cannot be chosen or changed at will, nor can they be "socialized" onto a person's body, it stands to reason that they are passed on to us genetically, even though they do not ALWAYS mirror our parent's. This obviously being the case, it's not at all difficult to assume, then, that the traits that involve sexual orientation are passed on to us similarly, and with similar inexplicable variations. Anyone with even a little intellectual honesty, and an ability to reason, will conclude the same.