The traditional Judaeo-Christian view that homosexuality was caused by mingling with non-Israelite tribes, man's rebellious or fallen nature, or demonic temptation has given way to scientific explanations which regard homosexuality as normal and natural. Scientists are now in agreement that homosexuality is not 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 the scientific knowledge available on the genetic, biological and psychological causes of homosexuality.
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.
Genetic studies
Twin Studies
Biological Studies not strictly dealing with genetics
Interplay of the environment and the biological make-up of the individual. (Nature vs. nurture)
Various psychological views will also be examined.
The world's various religions have differing views on homosexuality; this topic has its own entry entitled Religion and homosexuality.
This entry is only about causal theories. It is not for discussing issues of morality, ethics, human rights, religion, etc. This is not a place to make a point about supposed "sins."
See also heterosexuality, homosexuality, bisexuality, zoophilia
/Debate is where any anything else will get moved