SCIENTIFIC AMERICAN - Feb 13 - Genetic matchmaking is entering the mainstream. Earlier this year, Nozze, a Japanese dating service, established a DNA Matching Course and hosted a related DNA Matching Party. For 86,400 yen ($790), men are paired with prospective dates based upon 16K variations in HLA gene complexes. There is also Swiss pioneer GenePartner, Houston-based Pheramor and services that combine genetic and non-genetic profiles like Instant Chemistry and SingldOut. Since the 1970s, researchers have found that variations in the genes of the major histocompatability complex (MHC) play a role in mate selection in mice. Swiss biologist Claus Wedekind did a study known as the sweaty T-shirt study. Researchers had men wear T-shirts for extended periods of time. Then they had women sniff the shirts to rate the former wearer's sexual attractiveness. They found an inverse correlation between MHC similarity and attraction score. Harvard geneticist George Church has championed another version of compatibility. Using whole genome sequencing, he hopes to match couples to reduce or eliminate many inherited diseases.