As one scientific review of the entire body of data concluded, “the mixed evidence …

Similarly, a 2006 study found that the more differences in MHC genes between a romantic couple, the more likely the female partner was to be sexually satisfied and committed to her existing relationship.

Yet, as noted above and as is common for most genetic research, especially as it relates to complex human behaviors such as love and romance, the data supporting genetic attraction is highly inconsistent.

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.

While genetics seems to play some role in human sexual attraction, it clearly is not the only, or even predominant, factor determining human mate choice.

This might argue for a heightened awareness of the importance of keeping a relationship on a positive keel.

Genetic affinity testing may also have some marginal benefit for new matches, where singles make choices with limited knowledge about potential partners.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.It will be a challenge for each of us, the media, and companies marketing products to put this information in proper context, not ignoring it completely, but also not giving it more weight and significance than it merits.(To its credit, Instant Chemistry isn’t just about genetics—it also relies on a personality assessment as part of its compatibility calculation, which assesses a registrant’s social tendencies, dominant and submissive inclinations, and intimacy.) Genetic affinity testing provides an opportunity to start exploring some of the genetic influences of our lives that have long been shrouded in darkness and mystery.Singld Out claims that genetic tests can identify up to 40 percent of the chemistry of attraction between two people.