Okay, Rome was an Empire for 450 years before its first recorded divorce. It took less than 300 years for the Roman Empire to start to decline after it started importing Greek slaves to educate their children in the Greek ethic of male sexuality. You can see the same decline in the British Empire, which reached its hieght under Queen Victoria in the late 19th century only the decline in the British Empire tool less than 75 years following the sexual scandals including homosexual scandals of the early 20th century.
Gay activists love to point to Sparta and the ultimate gay culture, however, they fail to share that Sparta artificially seperated the sexes at age 7 when boys started their military training. The sexes were never allowed to develop normally since even after reaching puberty the males lived in barracks. Even after reaching the age of 30 and being wed they were not allowed to live with their wife and were required to sneak out of their barracks to consummate the marriage and were severly disciplined if caught as this also was used as military training.
Athens winked at homosexual behavior as long as an Anthenian citizen did not engage in passive homosexual sex, which was grounds for loss of citizenship if proven. So, you see even historically homosexuality has never been promoted as a viable exclusive alternate lifestyle even by the Greek cultures of old.
After the APA removed homosexuality from the DSM III in 1973 all peer reviewed research was squelched. In the last 5 years psychologists and psychiatrists have begun to publish studies that show homosexuality (in some men and women) has psychological roots. Gay activists just love to show these studies can't show 100% conversion, however, of the hundred or so ex-gay men I know personally none have consulted a mental health professional simply because we don't trust them. So any results will be slanted by those who seek counseling for reasons (family, religious, or societal acceptance) that are not strong enough to motivate true change.
As to evidence to show homosexuality is genetic there is absolutely none other than anecdotal evidence, which gay activists appeal to and that these same gay activists and both APA's reject when used to show homosexuality is not genetic and can in fact be traced to environmental causes.
This is a complicated subject and to try to reduce it to "opinions" that are controlled more by biased and liberal mental health professionals and that create an environment where those who have changed simply keep to themselves and therefore are not numbered in studies out of fear of reprisals and exposure of their past calls any real opinons of the liberals into question, at least in my mind.