This is simply not true. There is no evolutionary cause that rationalizes prejudice against gay people. The simple fact that homosexuality has been observed b

This is simply not true. There is no evolutionary cause that rationalizes prejudice against gay people. The simple fact that homosexuality has been observed by individuals in many species without similar reactions says a lot. Ancient Greece and Rome did not have significant stigmas against homosexuality, although it may not have been as common as some stories would suggest. Native Americans tended to respect homosexuals because they contributed to the tribe and helped care for the tribe's children - they put in more than they received. Prejudices against homosexuality coincide with the development of monotheistic religions, first with the Jews when the old testament was written, and this continued with the development of Christianity and Islam as they also consider the old testament to be a holy text. Modern Asia (specifically regarding China and Japan, but others as well) still has some issues with homosexuality despite not having the same religious influence, but those cultures tend to strongly emphasize conformity and not standing out. These cultures also tend to still expect the elderly to be taken care of by their children, while the Western world has moved towards helping the elderly retain as much independence as possible rather than mixing multiple generations together.