When we ask organizations and websites to stop claiming that queerness can never be a choice, a common response we receive is that it's necessary to make such a claim for the sake of warning people against ex-gay ministries. This page explains why acknowledging the possibility that some people choose to be queer is not, in fact, at all incompatible with continuing to warn of the ineffectiveness of ex-gay ministries, and can even make such warnings more effective.
Most gay, lesbian, or bisexual people who attempt (with or without an ex-gay ministry directing their efforts) to become heterosexual fail, and a great many such people feel that their attempts caused them a lot of unnecessary emotional stress. These are established facts that can be verified by surveying random samples of people who have attempted to become heterosexual. No one, regardless of whether or not they consider their queerness a choice, can reasonably deny these facts. But this does not justify drawing a much broader, more dangerous, and unprovable conclusion: "Sexual orientation is never a choice."
First of all, it's a basic rule of rhetoric that sticking to provable facts makes for a far more convincing argument. If you're speaking to a parent who's convinced that an ex-gay ministry can help their child, repeating a slogan phrase like "Sexual orientation is not a choice" (or even the slightly less broad but still unprovable claim that "No ex-gay ministry anywhere has ever successfully turned even one gay person heterosexual") accomplishes nothing—you cannot prove it to them, and the fact that you make the assertion without proof to back it up with only makes you come across to the parent as being biased. On the other hand, if you sit down with this same parent and refrain from making any unprovable assertions, but simply go over the proven statistics on the huge percentage of gay people who drop out of these ministries and very much regret having ever subjected themselves to such homophobic environments, then you are far more likely to impress the parent as being someone who is speaking objectively and has good solid reasons for warning them away from ex-gay ministries.
Second, generalizing that "sexual orientation is not a choice" based solely on the high failure rate of queer people who attempt to become hetero is ridiculous. Choosing to be queer and choosing to be hetero should be considered two extremely different phenomena, for the simple reason that society does not define queerness and heterosexuality in symmetrical ways. For example, a person who chooses to be queer is not usually under tremendous social pressure to become queer, nor running away from some overwhelming internalized heterophobia, nor under any great deal of pressure to hide and lie about their former heterosexual life in order to "fit in" with other queers and prove themself to be "really" queer. A person who chooses to be queer is usually free to casually mention that opposite-sex marriage they had a few years ago, and their queer friends will never think them any less queer for it. A person who chooses to be queer is not at all likely to be wracked with permanent guilt and shame for having formerly "succumbed" to "heterosexual temptations." So what does choosing to be queer have in common with ex-gay "reparative therapy"? Virtually nothing. It is absurdly unfair to use evidence that relates only to ex-gay "reparative therapy" as a reason to accuse proud queers who say "I chose to be queer" of not knowing what we're talking about—and worse yet, to tell our parents and the whole world of people who visit a PFLAG chapter website or other resource supposedly intended to help us that we don't know what we're talking about.