*nod* I refuse to use the nature/"I can't help it" argument about being queer, too, so I tend to use arguments similar to these myself.

(I hate the implied apologism of "I can't help it" -- it implies that if we could, we should, and they should just get right on that "cure for teh gay" project. It also fails to protect bi people in any substantial way, let alone any of the many other choices we make about sexuality. Biology may well be a factor, but I'm not going to base my defense on it.)