Homosexuality is natural

There's some quite interesting stuff coming out of the US supreme thing with marriage equality right now. 

The argument by the churches is that homosexuality is unnatural. I dunno if they're completely blind to science, but it's well known that homosexuality abounds in nature. So how do they say it's unnatural then?

This article from the New York Times gives a description of the various sexual activities happening in nature right outside the Supreme Court, and sums up thus: 

Stepping from the northern border of the Mall into the Smithsonian's National Museum of Natural History, we come face-to-taxidermied-face with our great ape relatives. Before these apes were sequestered in museum cabinets, homosexual bonds were a natural part of their lives. This is especially true for our closest living cousins, the bonobos and chimpanzees. 

The facts of biology plainly falsify the oft-repeated notion that homosexuality is unnatural. Every species has evolved its own sexual ecology, and so nature resists generalizations. Does humanity's natural inheritance include homosexual bonds and behaviors? Certainly. This conclusion is reinforced by the growing evidence that our sexual orientation is influenced by both our genes and the environment that we experience in the womb. 

A wide, living rainbow arcs across the natural world. Diversity rules in sexuality, just as it does in the rest of biology. This natural variety does not provide ready-made moral guidance. But to claim that the only natural forms of sex and pair bonding occur between unambiguous males and females is to ignore the facts of human biology. Let those who wish for marriage to be "founded in nature" take note: the view outside the Supreme Court is full of life's beautiful sexual variegation. more