Relationship quizzes in magazines are fun, but a test for genetic compatibility might be the better way to see if your wife or girlfriend will cheat on you.
When it comes to choosing a mate, opposites really do attract, according to new research that shows people are subconsciously more likely to choose a partner whose genetic make-up is different to their own.
A Brazilian study presented at a conference in Europe in June has found evidence that married couples are more likely to have genetic differences in a DNA region governing the immune system than were randomly matched pairs.
The study backs up other research done at the University of New Mexico which found genetic differences could possibly explain romantic chemistry and even whether woman was likely to be unfaithful. Couples in which the individuals had dissimilar versions of so-called MHC genes had the greatest sexual compatibility.
More robust babies
Scientists believe genetic difference gives couples a better chance of healthy reproduction, because with greater variations the immune system can recognise a broader range of foreign (or invader) cells, making the offspring more able to ward off infections.
Scientists say it was not clear what signals attract the body to people who are genetically different.
Previous studies have suggested animals may use body odor as a guide to identify possible mates as being genetically similar or dissimilar, but other physical factors like facial symmetry may also be involved.
Similarity a sexual turn off
The University of Mexico study found the attraction between opposites was strongest when women were most fertile. “As the [MHC] similarity increases, women are more turned off toward the guy sexually and more likely to be fantasizing about other men, specifically when she’s at the fertile point in her cycle,” said study team member Randy Thornhill, a biologist at the University of New Mexico.
Not only did they fantasize, but women in similar-MHC relationships reported more sexual encounters outside with other men.