Homosexuality is romantic attraction, sexual attraction, or sexual behavior between people of the same sex or gender. As a sexual orientation, homosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" exclusively to people of the same sex or gender. It "also refers to a person's sense of identity based on those attractions, related behaviors, and membership in a community of others who share those attractions."
Along with bisexuality and heterosexuality, homosexuality is one of the three main categories of sexual orientation within the heterosexual–homosexual continuum. Although no single theory on the cause of sexual orientation has yet gained widespread support, scientists favor biological theories. There is considerably more evidence supporting nonsocial, biological causes of sexual orientation than social ones, especially for males. A major hypothesis implicates the prenatal environment, specifically the organizational effects of hormones on the fetal brain. There is no substantive evidence which suggests parenting or early childhood experiences play a role in developing a sexual orientation. Scientific...