People are more likely to marry others with similar genes, new research led by the University of Colorado's Boulder campus has found.

The researchers compared married pairs to non-coupled pairs and found that spouses are more genetically similar than two randomly selected individuals.

Scientists long have known that people tend to marry those who are similar to them in religion, age, race, income, education and other factors. This study, published today in the journal Proceedings of the National Academy of Sciences, is a new attempt at measuring people's preference for genetic similarities.

No existing research has analyzed how much married pairs are genetically similar to one another across the entire genome, according to the study.

The research also describes the relationship between genetic preference and educational preference, and finds that educational similarities still trump genetics.

Domingue and Jason Boardman, researchers in CU's Institute of Behavioral Science, found that genetic similarity between spouses is roughly one-third the magnitude of educational similarity.

"We know that people tend to marry individuals that are like them in terms of education level," said Benjamin Domingue, the study's lead author. "Education is heritable, so there's this idea that genes explain some of the variability in education.

"Our question is, basically, do we observe a genetic preference when it comes to spouse selection, and, if so, how does that compare and interact with education?"


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This research could have implications for statistical models used to predict the role of genetics in health and disease in families and populations. Those models traditionally have assumed that mating is random with respect to genetics, which isn't painting an entirely accurate picture, Domingue said.

"This research is meant to probe that assumption," he said. "Is it actually true that mating happens at random with respect to genotype and if not, how badly violated is that assumption?"

To analyze genetic similarities, the researchers used data collected by the University of Michigan's Health and Retirement Study, a longitudinal survey of 26,000 Americans older than 50 every two years.

They looked at the genomes of 825 non-Hispanic, white American couples. A natural extension of this study is to look at the genetic similarities of couples in other cohorts, such as same-sex pairs, cross-race pairs and non-white pairs, Domingue said.

He's also interested in looking at how genetic similarities factor into friendship formation.

Other studies might offer a more nuanced look at which regions of the genome are similar among couples and which are different and why.

Contact Camera Staff Writer Sarah Kuta at 303-473-1106, kutas@dailycamera.com or twitter.com/sarahkuta.