The Gay Germ

The genetics of male homosexuality came up on a mailing list recently, so I had the opportunity to push the plague perspective, or as it is more commonly known, the gay gene theory or pathogenic hypothesis. Nor is the gay germ alone among infectious causes of personality:

Cochran claims that theories of the cause of narcolepsy - that it is an auto-immune disease triggered by a virus - make the mechanism of selective brain modification plausible. He also claims that only humans and sheep exhibit homosexual behavior at population levels near 1% or greater. He says that given their physical proximity, it would be plausible to expect a pathogen that affected both species.
Proponents cite increasing evidence that some cases of Schizophrenia may be linked to exposure with Toxoplasma gondii. Other studies suggest that a variety of mood disorders may be linked to Borna Virus.