Wait, what? By this measure, Crohn's Disease is a lifestyle choice. So is mad cow disease (do cows make lifestyle choices?). And so on. I'm not equating homosexuality with disease here; I'm pointing out that not being testable in no way implies that something is a conscious choice.
And it's not even true. There are measurable differences in brain structure:
Symmetry Of Homosexual Brain Resembles That Of Opposite Sex, Swedish Study Finds. While some studies have left open the question of whether the structural differences cause homosexuality or are caused by it, the final sentence of the
study abstract is telling.
Here's another article examining the debate, noting that the brunt of the argument for a "learned " homosexuality is not born of hard science:
Homosexuality: Nature or Nurture in AllPsych Journal. Note that this article was written 5 years before the study results cited above were published.
What? So same-sex couples are now doing something wrong if they don't have children?
Torben