A large number of studies, involving different experimental methods and populations, have now been reported, and they give discordant results.
A few studies have found that humans prefer sexual partners with only moderately different or even similar MHC variants, others have found that MHC diversity is detected by facial shape rather than smell, and still more have found that women in committed relationships are most attracted to men with different MHC alleles.
Some studies have also discovered that women on birth control pills tend to prefer men with the same MHC variants, the opposite of their peers not on the pill.
A leading hypothesis is that such “disassortative” mating will produce offspring with greater diversity in their MHC genes that will protect them against a broader range of pathogens.
Given that all mammals display similar genetic mechanisms, one might expect a similar genetic attraction to exist in humans, albeit within the context of the greater complexity of human relationships.
Unlike some direct-to-consumer genetic testing companies (such as those claiming to offer genetically tailored nutritional supplements, which have been subject to enforcement by the Federal Trade Commission for deceptive claims), there is some legitimate science behind the new DNA-matching dating websites.