Why do they bug me? Because the premise behind studying the why of sexual difference is unfair. When we decide to look for the cause of queer sexual orientations to me that says "here we have a problem. let's find the root cause!" Queer sexualities are not a problem, or an abnormality, or a disease that we need to cure.Queer sexualities are a problem for science, where everything not well-understood is referred to as a problem.
As for the "abnormality" thing, let's appreciate that most people aren't queer. But so what if some people are? The chips have fallen in such an arrangement where we've got gay people all around us. In itself, this is not morally meaningful. It makes you think a little about how the term "deviant" is used in our culture, and how much importance we place on conformity.
I kinda hate to do it, but I have to refer back to a post I wrote last summer about this subject (In which, I feel complelled to explain, the "zombie fat" subject was a bit of a tangent, and not me stamping my feet and demanding everyone believe it.) I said:
I have a lot of faith in my socio-political understanding of the world. I think that my feelings about equality and justice and race and gender and class are borne out by reality. This is sometimes true because the reality that controls how these things affect us is entirely human-created: why would we want to use a legal system that puts men and women on unequal footing? Other times, it's empirically true: women are perfectly capable of changing the oil in their cars.So when some conservative who fancies himself a rebel brings out the "dangerous truths" that liberals can't handle, I shrug so hard that people think I'm having a seizure.*
*I swear, I'm not. I just took my Keppra, thanks.