For some time now, scientists have been looking for a genetic or hormonal cause of sexual orientation. Thus far, no "gay gene" has been found -- at least not in terms of incontrovertible and accepted science. Yet, it is now claimed that a growing body of evidence indicates that biological factors may at least contribute to sexual orientation.

The most interesting research along these lines relates to the study of sheep. Scientists at the U.S. Sheep Experiment Station are conducting research into the sexual orientation of sheep through "sexual partner preference testing." As William Saletan at Slate.com explains:

A bare majority of rams turn out to be heterosexual. One in five swings both ways. About 15 percent are asexual, and 7 percent to 10 percent are gay.

Why so many gay rams? Is it too much socializing with ewes? Same-sex play with other lambs? Domestication? Nope. Those theories have been debunked. Gay rams don't act girly. They're just as gay in the wild. And a crucial part of their brains--the "sexually dimorphic nucleus"--looks more like a ewe's than like a straight ram's. Gay men have a similar brain resemblance to women. Charles Roselli, the project's lead scientist, says such research "strongly suggests that sexual preference is biologically determined in animals, and possibly in humans."

What makes the sheep "sexual partner preference testing" research so interesting is that the same scientists who are documenting the rather surprising sexual behaviors of male sheep think they can also change the sexual orientation of the animals. In other words, finding a biological causation for homosexuality may also lead to the discovery of a "cure" for the same phenomenon.

That's where the issue gets really interesting. People for the Ethical Treatment of Animals [PETA] has called for an end to the research, while tennis star Martina Navratilova called the research "homophobic and cruel" and argued that gay sheep have a "right" to be homosexual. No kidding.

Homosexual activists were among the first to call for (and fund) research into a biological cause of homosexuality. After all, they argued, the discovery of a biological cause would lead to the normalization of homosexuality simply because it would then be seen to be natural, and thus moral.

But now the picture is quite different. Many homosexual activists recognize that the discovery of a biological marker or cause for homosexual orientation could lead to efforts to eliminate the trait, or change the orientation through genetic or hormonal treatments.