Scientists have long been puzzled by homosexuality, as it seems to be at odds with the basic human drive to reproduce. Various theories have been offered--from the notion that homosexual men make more diligent uncles than their heterosexual counterparts (and thus are better at ensuring the survival of their relatives) to the notion that the same gene that codes for homosexuality in men makes women more fertile. Now researchers from the University of Portsmouth in England have put forth a controversial new theory.