Actually, the entire question sent the APA into a tizzy of trying to define just what a mental illness was in the first place and whether or not there is any such thing - which goes to show how totally worthless the APA is.
One sign of a mental illness is an inability to accept reality. If I were to declare myself Napoleon, and to insist that France accept me as their Emperor, that wold be a sign of mental illness since I am not the Emperor of France. (It would also be a sign of mental illness because who would want to be? But I digress.)
Everyone is born in a heterosexual body. That's reality. The claim to be homosexual is an inability to accept reality. That's a mental illness. Fortunately it can be treated. Just as I no longer demand that France enthrone me, former homosexuals live happy heterosexual lives.
Of course, I won't deny that I miss the lavish parties they used to throw for me at the palace, but really, I'm doing quite well now, thank you.
Shalom.
Perfect place for the quote of the day!
"France has neither winter, nor summer, nor morals. France is miserable because it is filled with Frenchmen, and Frenchmen are miserable because they live in France." --Mark Twain