Individuals are more genetically similar to their loved ones than they are to randomly selected persons from the same population, finds a study by University of Colorado Boulder.
Scientists knew that people tend to get married to those who have similar characteristics, including religion, age, race, income, body type and education, among others.
Scientists also found that people are more likely to pick mates who have similar DNA.
A new study published in the this is the journal Proceedings of the National Academy of Sciences, the first study to look at similarities across the entire genome.
Domingue, his colleagues and CU-Boulder Associate Professor Jason Boardman,looked specifically at single-nucleotide polymorphisms, which are places in their DNA that are known to commonly differ among
humans. The researchers examined the genomes of 825 non-Hispanic white American couples. They used genomic data collected by the Health and Retirement Study, which is sponsored by the National Institute on Aging.
"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. "But there's been a question about whether we mate at random with respect to genetics."
The researchers came to an astonishing conclusion, there were lesser differences in the DNA of the married couples than between any two people selected at random. They found this estimated genetic similarity between people after using 1.7 million single-nucleotide polymorphisms in each individuals genome.
The researchers compared the magnitude of the genetic similarity between married couples 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 one 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 study also forms a foundation for future research that could explore whether similar results are found between married people of other peoples such as Indians, 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.
This study has opened up countless possibilities to be explored. We have barely scratched the surface.