"When did you choose to be queer?"
"Sometime in the spring of 2012. I don't remember the month. It was definitely a weekday, though."
I don't actually think 'choice' is particularly relevant to morality. By which I mean that while it's vitally important to protect the right to choice (autonomy, self-identification, consent--these are not optional) I don't generally think something becomes more moral or less moral because it's a matter of choice. And one of the most common places we see this is in talking about whether it's okay for lesbians to get with other ladies, or whether it's okay for trans men to transition, or et cetera et cetera heterocisnormativity.
"These people are choosing to act in unnatural ways!"
"But it's perfectly natural; they're born that way. You don't choose to be straight, do you?"
No, stop, back up. This is a derail, and it's one that we've spent too long allowing, and it's one that plays against the kinds of choice that are important, and it doesn't win us much anyway.
It doesn't matter if being queer is a choice.
It doesn't matter.
It's not a choice; anyone can tell you this, but that's not the point to fight. What matters is that ending discrimination is a good thing, and allowing people to consensually love and marry and boff is a good thing, and allowing people to be themselves is a good thing. The law already tells us who can consent to what and who can't. Job done, game over, high scores all around. It doesn't need to be any more complicated than that.
If we keep hyping up how important it is that there is no Queer Choice, we lose ground in two important ways. First, we leave open the notion that if there were a choice involved, it might somehow become okay to discriminate against gay men because, after all, they decided not to conform. (This just in: racism would still be stupid even if every human in the world had the power to snap their fingers and turn white.) And secondly, it helps people who keep bringing up even stupider arguments, like arguing that marriage equality some kind of 'gateway right' and soon we'll be legalising incestuous marriages and sex with ducks. As if the only reasons we have problems with those things are because they're 'unnatural', rather than obviously harmful and consent-unfriendly.
We know that people can have inborn tendencies toward terrible things that are totally unrelated to sex, so we have reason to think there are inborn tendencies towards terrible sexual things. 'Born that way' is not relevant to the morality. Kleptomania is real; that doesn't make stealing morally appropriate (although it does have significant impacts on how people need to teach themselves and choose to respond and et cetera my point is not that mental illnesses are morally suspect either just so's we're clear on that). Rape culture narratives tell us that men can't help being aggressive and hostile when they want to make with the boning, because they're 'born that way'. To hell with 'born that way' as having relevance to sexual morality. What matters is: does this hurt anyone and does it help anyone? And all else equal, sex and gender queerness gets a pass on that.
There are plenty of bigots who have already fully embraced the 'born that way' aspect and still don't care. From this we get the Side B Christians who believe that gay people exist but that it would still be wrong for them to act on their nature (the only kind of romantic/sexual attraction they experience) because apparently sometimes their Creator just likes to screw with them. So even buying into 'born that way' doesn't actually guarantee any kind of acceptance; sometimes it just means they treat the desire of girls to kiss girls the same way they treat a heroin addiction. Awesome.
In case I don't already bring this up enough: I'm bi. (I am not pansexual, but I'm pretty sure this applies to anyone who is, too.) I like girls enough that I was able to get through about 27 years without even acknowledging that I like guys too. If anyone does have a choice, I do: I could probably limit myself to relationships with women and end up just about as happy as I would be if I considered both women and men. If I date a guy, it's not going to be because I have no other choice, it's going to be because I've said okay, this is a thing I could try: let's run with it. That's not immoral either.
And I'm no expert on trans issues, but it seems to me that a huge emphasis on being 'born that way' is of less-than-zero help to people who already have to fight to define their identity in any way other than according to the assumptions made by other people at the time of their birth.
'Born that way' is deterministic, and that's a problem for anyone who doesn't fit into the popular categories. The people who have any kind of fluidity in their identity (attraction to more than one gender, or transition through more than one gender identity) already get sidelined constantly when it comes to the supposed rainbow of diversity. There's no such thing as a 'bisexual relationship'--it's a superposition (to get quantum mechanical again), it's being in a state of appearing either straight or gay until suddenly you aren't. I have genderqueer friends who've done their best to help me understand the idea of feeling male one day and female another and genderless a third, and suddenly 'born that way' isn't a checkbox but a probability distribution or a Venn diagram and it's still all harmless and it's still okay.
'Born that way' play into the idea that people don't change, can't change, shouldn't change, and I don't believe that, and I'm very done with ceding that point to bigots in the hopes that it will somehow encourage them to change.