I did see this, Mack, I just haven't had time to think about it.
It's obvious to any intelligent person that they choose it. Their train of thought must go like this: "I find sex with people of my own sex repulsive. But I will force myself to do it, and pretend that I like it, because I know that it irritates the bejeezus out of fundamentalists. Matter of fact, I will move in with someone of my own gender, and pretend that I'm in love with them, because I want to make a political statement." Who could believe that they don't choose it? Why, it's the logical answer. I mean, they couldn't really be innately attracted to people of their own gender through no volition of their own. Could they?
If its not a choice they must have magnetic pelvic bones.