when did the belief that one is "born gay" become "contemporary"?
i'm assuming you take that as the prevailing verdict on the origins of homosexuality?
It is the contemporary stance that homosexuality* is a product of nature because most of the evidence in support of this position has been gathered during the last decade and a half. What have we learned?
Homosexuality exists in hundreds of species.
Shared sexuality is higher among identical twins than among fraternal twins.
Altered prenatal hormone exposure seems to lead to homosexuality in humans.
Researchers have altered the sexuality of fruit flies with genetic manipulation.
Gay men have brains, which are in some ways more similar to heterosexual women than to heterosexual males.
Gay men have spatial abilities closer to females than males. Lesbians are closer to straight males in this mental ability.
Homosexuality seems to run in the maternal side of the family.
Gay men and women react similarly to the smell of sex-related hormones.
*That's not to say sexual
behavior can not be a product of culture , but sexual orientation seems to be a product of nature.