Homosexuality refers to sexual attraction or sexual behavior between people of the same sex, or to a sexual orientation. As an orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions primarily to" people of the same sex; "it also refers to an individual’s sense of personal and social identity based on those attractions, behaviors expressing them, and membership in a community of others who share them."
Homosexuality is one of the three main categories of sexual orientation, along with bisexuality and heterosexuality, within the heterosexual-homosexual continuum. The number of people who identify as homosexual — and the proportion of people who have same-sex sexual experiences — are difficult for researchers to estimate reliably for a variety of reasons. In the modern West, major studies indicate a prevalence of 2% to 13% of the population.
A 2006 study suggested that 20% of the population anonymously reported some homosexual feelings, although relatively few participants in the study identified themselves as homosexual.
Psychology was one of the first disciplines to study homosexuality as a discrete phenomenon. In the late 19th and throughout most of the 20th centuries, pathological models of homosexuality were standard. On December 15, 1973, the American Psychiatric Association, removed homosexuality from its official list of mental disorders. The American Psychological Association Council of Representatives adopted the same measure on January 24-26, 1975.
The first attempts to classify homosexuality as a disease were made by the fledgling European sexologist movement in the late 19th century. In 1886 noted sexologist Richard von Krafft-Ebing listed homosexuality along with 200 other case studies of deviant sexual practices in his definitive work, Psychopathia Sexualis. Krafft-Ebing proposed that homosexuality was caused by either "congenital [during birth] inversion" or an "acquired inversion".
In the last two decades of the 19th century, a different view began to predominate in medical and psychiatric circles, judging such behavior as indicative of a type of person with a defined and relatively stable sexual orientation. In the late 19th and early 20th centuries, pathological models of homosexuality were standard.
Today, according to American Psychological Association:
“Psychologists, psychiatrists, and other mental health professionals agree that homosexuality is not an illness, a mental disorder, or an emotional problem. More than 35 years of objective, well-designed scientific research has shown that homosexuality, in and itself, is not associated with mental disorders or emotional or social problems. Homosexuality was once thought to be a mental illness because mental health professionals and society had biased information.In the past, the studies of gay, lesbian, and bisexual people involved only those in therapy, thus biasing the resulting conclusions. When researchers examined data about such people who were not in therapy, the idea that homosexuality was a mental illness was quickly found to be untrue. In 1973 the American Psychiatric Association confirmed the importance of the new, better-designed research and removed homosexuality from the official manual that lists mental and emotional disorders. Two years later, the American Psychological Association passed a resolution supporting this removal.”
The World Health Organization's ICD-9 (1977) listed homosexuality as a mental illness; it was removed from the ICD-10, endorsed by the Forty-third World Health Assembly on May 17, 1990. Like the DSM-II, the ICD-10 added ego-dystonic sexual orientation to the list, which refers to people who want to change their gender identities or sexual orientation because of a psychological or behavioral disorder.
There is no consensus among scientists about the exact reasons that an individual develops a heterosexual, bisexual, gay, or lesbian orientation. The main reasons cited include genetic and environmental factors, likely in combination. Other factors that may play a role include prenatal hormone exposure, where hormones play a role in determining sexual orientation as they do with sex differentiation; and prenatal stress on the mother.The American Academy of Pediatrics has stated that "sexual orientation probably is not determined by any one factor but by a combination of genetic, hormonal, and environmental influences".
The American Psychological Association has stated that "there are probably many reasons for a person's sexual orientation and the reasons may be different for different people". It stated that, for most people, sexual orientation is determined at an early age. The American Psychiatric Association has stated that, "to date there are no replicated scientific studies supporting any specific biological etiology for homosexuality. Similarly, no specific psychosocial or family dynamic cause for homosexuality has been identified, including histories of childhood sexual abuse". Research into how sexual orientation may be determined by genetic or other prenatal factors plays a role in political and social debates about homosexuality, and also raises fears about genetic profiling and prenatal testing.
Innate bisexuality (or predisposition to bisexuality) is a term introduced by Sigmund Freud, based on work by his associate Wilhelm Fliess, that expounds that all humans are born bisexual but through psychological development - which includes both external and internal factors - become monosexual, while the bisexuality remains in a latent state.In a 2008 study, its authors stated that "there is considerable evidence that human sexual orientation is genetically influenced, so it is not known how homosexuality, which tends to lower reproductive success, is maintained in the population at a relatively high frequency". They hypothesized that "while genes predisposing to homosexuality reduce homosexuals' reproductive success, they may confer some advantage in heterosexuals who carry them".
Their results suggested that "genes predisposing to homosexuality may confer a mating advantage in heterosexuals, which could help explain the evolution and maintenance of homosexuality in the population".
Homosexual behavior in animals
Homosexual behavior in animals refers to the documented evidence of homosexual, bisexual and transgender behavior in non-human animals. Such behaviors include sex, courtship, affection, pair bonding, and parenting. Homosexual and bisexual behavior are widespread in the animal kingdom: a 1999 review by researcher Bruce Bagemihl shows that homosexual behavior, has been observed in close to 1500 species, ranging from primates to gut worms, and is well documented for 500 of them.
Animal sexual behavior takes many different forms, even within the same species. The motivations for and implications of these behaviors have yet to be fully understood, since most species have yet to be fully studied. According to Bagemihl, "the animal kingdom [does] it with much greater sexual diversity -- including homosexual, bisexual and nonreproductive sex -- than the scientific community and society at large have previously been willing to accept."
No, homosexuality is not an illness, a mental disorder, or a disease.