Even the belief that heterosexuality is the statistical norm has been challenged by some research, starting with that of [Alfred Kinsey]?, which indicates most people's orientation falls along a gradual scale between the two extremes, and that societal influences cause a person to "choose" between one extreme and the other.
There has also been a realization that any attempt at understanding the causes of [sexual attraction]? to the same sex will be more successful if we understand the mechanisms that underlie sexual attraction per se, and more specifically what causes many people to feel sexual attraction primarily towards members of one particular sex.
Some early civilizations such as ancient Greece and the Roman civilization, often accepted homosexual behavior but, in general, did not make a distinction between homosexuality and heterosexuality as orientations. Homosexual and heterosexual responses were considered to both be "natural" feelings that manifest to a greater or lesser degree in different individuals. The Greek civilization in particular considered it quite natural for young men to have older mentors with whom sexual interaction was accepted. There was no real inquiry into the causes of sexual orientation, because they didn't have the concept of sexual orientation at all.
The traditional Judaeo-Christian view that homosexuality was due to man's rebellious or fallen nature, or demonic temptation has given way to scientific explanations which regard homosexuality as natural. Scientists are now questioning the view that homosexuality is a freely made choice or "lifestyle" that someone decided to follow, and many religions are updating their theologies to conform with science.
The last 20 years have seen an explosion in scientific research into the genetic, biological and psychological causes of homosexuality. Most research looks at human sexuality, but homosexual behavior has been observed in non-human animals as well as in humans.
Some research suggests that there are genetic causes which make people more likely to become homosexual.
It is unknown how many types of genetic variations lead to homosexuality. It is also unknown whether and to what extent any one's genes compel the development of homosexuality. Many other biological factors may be involved. The following topics need to be elucidated in this entry, with references to imporant scientific and medical journal articles, and books which summarize said articles.
Some research has also looked at non-genetic biological factors such as hormonal factors and the development of the foetus within the womb.
Some researchers have surveyed homosexuals to learn how social and psychological influences might have influenced their sexual orientation. In surveys of gay men and lesbians, the majority assert that they were born that way. Most of them report that they knew they were "different" from an early age, often by puberty and not uncommonly in prepubescence. Instances of individuals stating that they chose to be gay are extremely rare. Anecdotal evidence such as this doesn't give any insights into the nature vs. nurture debates, but it is considered by many to be strong evidence that orientation is not a choice.
The world's various religions have differing views on homosexuality; this topic has its own entry entitled Religion and homosexuality.
See also heterosexuality, homosexuality, bisexuality, zoophilia
/Debate is where any anything else will get moved