In 1974, a group of, "mental patients", made enough noise to get pulled out of the DSM. The DSM is the Diagnostic and Statistical Manual of Mental Disorders, this is the bible of psychology. A reference manual used by psychologists to classify all known mental disorders. What group are we talking about? Homosexuals. For those that don't know. Homosexuality was considered a mental disorder by Sigmund Freud. Freud was an Austrian Neurologist, and considered the founding father of psychoanalysis. He said a whole bunch of things about a whole bunch of stuff. Google can tell you all about him.
Freud's belief on homosexuality was that children learn what is to be considered normal sexual behavior in life. Those that don't, or cannot control themselves enough to conform, have a mental disorder. One that can be "repaired", if the disorder was effecting the patients life in a negative way. Now this guy was born in 1856. So why did they keep his ideas until 1974? Science hadn't proven him wrong yet and still hasn't. We are talking about the only mental disorder to be removed from the DSM, because the group with the "mental disorder" decided they didn't have one. It was put to a vote by the board overseeing the manual's content. The vote barely passed 50%. Where did this happen? San Francisco. This meaning the vote could have been corrupted by outside influence since the area had already boasted quite a homosexual population.
All that was said to say this. The opinion stands that homosexuality should still be considered a mental disorder. On the basis that it hasn't been proven otherwise. Imagine if all those people with bipolar disorder, anxiety, eating disorders, or depression said they don't belong in the DSM either, because most of them can live normal lives. They would be sent to a psychologist for an examination. I'm not saying homosexuals are crazy. I'm not saying anyone with a mental disorder is crazy. I'm saying this opinion stands for good reason. It may not be mine, but this is just the opinion given by one man.
A good article that stands on this point is here. It is written by a doctor of psychology. It is where I got a lot of this information. What I didn't should be common knowledge or information that is available from many sources. Google is a wonderfully free encyclopedia.