Partners in a spousal relationship share a greater degree of genetic similarity than do randomly selected, non-coupled pairs of individuals, according to a new study co-authored by La Follette School professor Jason Fletcher.
“The results suggest that couples may seek mates who share a similar level of education and are more genetically similar to themselves than individuals selected randomly,” Fletcher says.
Fletcher, Benjamin W. Domingue of the University of Colorado Boulder and others compared the genetic similarity of American spouses in 825 non-Hispanic white heterosexual pairings with the genetic similarity of non-coupled pairs of individuals. They found that spousal couples are more genetically similar than non-coupled pairs, a phenomenon called genetic assortative mating.
Previous research indicates that individuals may select spousal partners with a similar level of education to themselves, a phenomenon known as educational assortative mating, Fletcher says. “We did additional analysis that revealed that the strength of the association between genetic and spousal choice was only one-third that of the association between education and spousal choice.”
The authors also identified a possible link between genetic and educational assortative mating, concluding that genetic similarity may account for some, but not more than 10 percent of assortative mating by education level. “Social barriers to mate choice did not appear to influence the degree of genetic similarity within couples,” Fletcher says, adding that the authors encourage broader analysis that would include additional races, interracial couples and homosexual couples.
The research is published in the Proceedings of the National Academy of Sciences.