A controversial decade-old study that seemed to suggest some gay people can become straight has been used by countless opponents of gay rights, who say it proves homosexuality is a chosen lifestyle.

But now the author of that study says it was flawed, and he’s apologized to the gay community for the heartache it’s caused them.

Back in 2001, Dr. Robert L. Spitzer interviewed 200 gay individuals who’d undergone so-called “reparative therapy” in an effort to become heterosexual. When some said it had worked, Spitzer reported those findings at an American Psychiatric Association meeting.

His presentation caused a stir not just because of the study itself, but because Spitzer had been a leading proponent in having homosexuality removed from the APA’s list of mental disorders some 30 years prior.

Now, though, he says that since the alleged gay-to-straight transformations relied solely on self-reported assessments by his study subjects, “there was no way to determine if [their] accounts of change were valid.”

In a letter to the editor of the Archives of Sexual Behavior, Spitzer wrote, “I believe I owe the gay community an apology for my study making unproven claims of the efficacy of reparative therapy … I also apologize to any gay person who wasted time and energy undergoing some form of reparative therapy because they believed that I had proven that [it] works with some ‘highly motivated’ individuals.”

[Associated Press]