White married couples in the U.S. tend to have similar DNA as opposed to random individuals from the same population, according to a recent study at the University of Colorado Boulder. Scientists previously knew that many individuals marry others with similar characteristics, such as age, race, religion, education, body type, and income.

The latest study results were recently published in the journal Proceedings of the National Academy of Sciences.

The study is the first of its kind to examine DNA similarities among couples across the entire genome.

Lead study author Benjamin Domingue, research associate at the University of Colorado-Boulder’s Institute of Behavioral Science, said in a statement, “It’s well known that people marry folks who are like them.” He continued, “But there’s been a question about whether we mate at random with respect to genetics.”

Dominique and colleagues used genomic data from the Health and Retirement Study, which is sponsored by the National Institute on Aging.

For the study, the researchers looked at the genomes of 825 non-Hispanic white couples from the U.S. The researchers specifically focused on single-nucleotide polymorphisms, DNA locations that tend to vary among humans, searching for “genetic assertive mating” among the provided DNA samples

Domingue concluded, “People with more similar genes end up having similar education, which places them in the same social situations and gives them a better chance to mate.”