Prior to and throughout most of the 20th century, common standard psychology viewed homosexuality in terms of pathological models as a mental illness.
That classification began to be tested in research, which hasn't produced strong empirical evidence regarding homosexuality as a disorder. A large number of professionals in medicine, mental health, and the behavioral and social sciences, "sit on the fence" regarding the classification of homosexuality as a mental disorder.
Gay rights groups continually assert that homosexuals are as “normal” as heterosexuals, that homosexuality is not an illness or psychological disorder.
Discrimination against lesbians or gays in society-at-large, workplace and social settings produce increased levels of anger, stress and anxiety providing fertile breedingground for depressive disorders and with youth, suicidal thoughts.
Years of research suggest that people can't change their sexual orientation because they want to, and that trying can cause mental anguish. What's more, some studies suggest that being gay may have a genetic or biological basis.
Whether or not you believe that homosexuality is a mental disorder, this video offers a neat scientific analysis of why homosexuality is not a choice...