This document discusses the history of how homosexuality has been classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM) from the first edition in 1952 to the fourth edition in 1994. It also examines various theories for the causal factors of homosexuality, including biological, genetic, prenatal influences, and psychosocial factors. Different psychological and biological treatment approaches are also mentioned, as well as topics relating to gender identity, sex, and sexuality.