Opposites attract? Not really. Science says that we tend to choose people who are more like us - not just in terms of income and education levels - but also in genetic make-up.
A study conducted by researchers at the University of Colorado Boulder found that people tend to pick mates considering genetic similarities.
Research has already shown that people are more likely to marry individuals with similar education levels. The phenomenon is known as educational assortative mating. In the current study, researchers found that genetic preference or genetic assortative mating is about a third of the strength of educational preferences. In other words, DNA matching plays an important role in mate selection.
"It's well known that people marry folks who are like them," said Benjamin Domingue, lead author of the paper and a research associate at CU-Boulder's Institute of Behavioral Science, according to a news release. "But there's been a question about whether we mate at random with respect to genetics."
The study was based on data from the Health and Retirement Study, which is sponsored by the National Institute on Aging.
Researchers looked at the genome of 825 non-Hispanic white American couples. The team specifically looked at single-nucleotide polymorphisms. SNPs are common points in DNA that differ among individuals.
Researchers found that married people were more genetically similar to each other than randomly selected individuals.
Related research has shown that people who have similar genetics have a happier marriage than others. The shared genetic make-up may explain, at least in part, why older couples tend to look similar.
The current study was funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the Office of the Director of the National Institutes of Health and is published in the journal Proceedings of the National Academy of Sciences.
Education and income preference plays a critical role in spouse selection. Indeed, recent research has shown that choosing people who are more like us in terms of income and social position has led to widening the gap between rich and poor.