Updated version of the field guide.
Human sexuality was poorly understood until the late 20th century. Before then, science was skewed by centuries-old homophobia. In an age when fewer gay people could be honest about their sexuality, most physicians only knowingly interacted with homosexuals who came to them seeking treatment for problems like depression and drug dependency, which led many 19th century doctors to assume that homosexuality was per se associated with mental illness.
As time went on, well-adjusted gays and lesbians became more visible and vocal. Realizing facts did not support anti-gay bias, the American Psychiatric Association removed homosexuality from its list of mental disorders in 1973, and before long every other professional medical organization in the U.S. followed suit. Problems like depression that disproportionately affect gay people were realized to be caused by the inordinate social pressures and discrimination gay people are subjected to, not by being gay itself.
Despite these advancements, prejudice dies hard. The Pseudoscientist is a right wing ideologue disguised as a scientist, who continues to portray homosexuality as a mental illness. He is usually unlicensed or has been kicked out of reputable organizations. He relies on discredited theories and self-publishes blatantly distorted research, spreading outrageous lies such as that gay people molest children more often, or on average die decades earlier than everyone else; lies that are often taken up and parroted by anti-gay religious organizations.
Despite his lack of credibility, the Pseudoscientist presents his research to homophobic politicians who use it to justify anti-gay propaganda and legislation. While religious leaders preach about sin, the Pseudoscientist provides the arguments that, by sounding vaguely scientific, sound more reasonable to Secular Homophobes.