Individuals are more genetically similar to their spouses than they are to randomly selected individuals from the same population, claims a new paper in Proceedings of the National Academy of Sciences.
This is much different than sociological factors - it is no surprised that people tend to marry others who have similar characteristics, like religion, age, race, income and education.
The conclusion was derived based on an analysis of genomic data collected by the Health and Retirement Study. They found that people also are more likely to pick mates who have similar DNA. While characteristics such as race, body type and even education have genetic components, this is the first study to look at similarities across the entire genome.
Basically, they think that social characteristics related to why we marry other people may also be genetic.
They examined the genomes of 825 non-Hispanic white American couples, looking specifically at single-nucleotide polymorphisms, which are places in their DNA that are known to commonly differ among humans. The scholars found that there were fewer differences in the DNA between married people than between two randomly selected individuals. In all, the researchers estimated genetic similarity between individuals using 1.7 million single-nucleotide polymorphisms in each person's genome.
The researchers compared the magnitude of the genetic similarity between married people to the magnitude of the better-studied phenomenon of people with similar educations 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.
Random genetic mating? Maybe not. It would have to include more than a few hundred white couples to determine it, though.