People more likely to choose spouses with similar DNA: study

People are more likely to marry those who have similar DNA, a US study finds, revealing genetics may also play a role in the so-called assortative mating.

It is well established that individuals are more similar to their spouses than other individuals on important traits, including religion, age, race, income, body type and education, among others. The genetic similarity between spouses, however, is less well understood.

In the new study, published in the US journal Proceedings of the National Academy of Sciences Monday, researchers from University of Colorado Boulder examined the genomes of 825 non- Hispanic white American couples.

They looked specifically at 1.7 million single-nucleotide polymorphisms, which are places in their DNA that are known to commonly differ among humans, in each person's genome.

The researchers found that there were fewer differences in the DNA between married people than between two randomly selected individuals.

The researchers also compared the magnitude of the genetic similarity between married people to the magnitude of the better- studied phenomenon of people with similar education marrying, known as educational assortative mating.

They found that the preference for a genetically similar spouse, known as genetic assortative mating, is about a third of the strength of educational assortative mating.

"The findings could have implications for statistical models now used by scientists to understand genetic differences between human populations because such models often assume random mating," the researchers said in a statement.

"The study also forms a foundation for future research that could explore whether similar results are found between married people of other races, whether people also choose genetically similar friends, and whether there are instances when people prefer mates whose DNA is actually more different rather than more similar," they added.