Genetics Also Play A Role In Mate Selection
May 20, 2014

Married Couples Tend To Have Similar DNA

Brett Smith for - Your Universe Online

Many of us might think, by looking at friends and family, that people tend to marry someone similar to them – and a new study in the journal Proceedings of the National Academy of Sciences (PNAS) has found that these similarities often go beyond more than skin deep.

According to the study, individuals and their spouses tend to be more genetically similar than they are to randomly chosen people. While previous studies have found that age, race and education level can all be contributing factors to spouse selection – this is the first study to look at similarities across the entire genome, the study authors said.

"It's well known that people marry folks who are like them," said Benjamin Domingue, lead author and a behavioral research associate at the University of Colorado-Boulder, in a recent statement. "But there's been a question about whether we mate at random with respect to genetics."

In the study, researchers used genomic information compiled by the Health and Retirement Study, which is backed by the National Institute on Aging. The scientists looked at the genomes of more than 820 non-Hispanic white American couples. They looked explicitly at single-nucleotide polymorphisms, which are locations in their DNA that are known to frequently differ among members of the population.

The scientists discovered that there were fewer inconsistencies in the DNA between couples than between two randomly-chosen individuals. In all, the scientists determined genetic likeness between individuals applying an analysis of 1.7 million single-nucleotide polymorphisms to each person's genome.

The scientists examined the degree of the genetic similarity between couples compared to the degree of people with very similar educations marrying, a phenomenon referred to as educational assortative mating. They discovered that the desire for a genetically comparable spouse, referred to as genetic assortative mating, is approximately a third of the power of educational assortative mating.

The team said their findings could have significance for statistical models now used by researchers to comprehend genetic inconsistencies between human populations as models often presume random mating.

The study also lays the groundwork for future study that could investigate if very similar results are identified between couples of other races, if people also select genetically very similar friends, and if there are situations when people choose mates whose DNA is more distinct instead of more very similar.

Another study on married couples published last year found that spouses are able to easily pick their partner’s voice out of a crowded room – but paradoxically, their voice is also easier to ignore.

Study researchers asked married couples between the ages 44 to 79 to record themselves reading scripted instructions out loud. Next, they asked the participants to put a pair of headphones on as they listened to the recordings of their spouses as it played simultaneously with a recording of another, unfamiliar voice.

They found that the familiar voice of a spouse stands out against other voices. However, they also found that spouses were also able to selectively ignore their significant other’s voice when trying to listen to a stranger. The researchers also discovered that as people get older, the harder it is for them to ignore their spouse when trying to listen to an unfamiliar voice.