Considering that homosexuality is found in nature, I would say that it's more natural than religious zealots like to make it out to be. There's lots of scientific proof of this type of behavior.
http://www.bidstrup.com/sodomy.htm
http://www.subversions.com/french/pa...e/animals.html
There have also been several books written on the subject. One that is particularly good, is Biological Exuberance : Animal Homosexuality and Natural Diversity, by Bruce Bagemihl. Interesting to check into.