Warren Blumenfeld discusses various historical theories about the origins and nature of homosexuality and gender diversity. He describes theories that attributed homosexuality to things like eating certain foods, ghost or worm possession, hormonal imbalances, inherited traits, or as a sign of societal decadence. Blumenfeld also discusses the origins of the terms "homosexual" and "heterosexual" and notes various flawed scientific theories and nonscientific beliefs about LGBTQ identities over time.