From the fact that there's more male bisexuality in societies other than America to a long history of situational homosexuality, from Greek pederasty to American West "brokeback mountain" moments, it's clear that, while inclinations to a gay/lesbian orientation are primarily genetic (and, in gay males, also, likely to some degree "environmental," but womb-environment affected) this is NOT a 100 percent genetic issue.
And I am totally with Frank Bruni -- a "gay orthodoxy" that says a Cynthia Nixon simply can't choose to be a lesbian is very, very, very wrong, in a number of ways.
Gay rights advocates should instead, in my opinion celebrate choice as well as nature in this issue. After all, this is ultimately about freedom, isn't it?
Even professional philosophers, or one at least, has/have the same take. Buying into the "it's in my gay genes" comes close to fundamentalist Christian ideas about original sin. It also undercuts claims of having science on one's side, if the science shows that choice is involved to a degree on sexual preference, level of activity within sexual preference, etc.
It's not as bad as "green" types excoriating the GOP for being anti-climate science while they're antivaxxers themselves. But, it's going down that type of road, at least to a degree.