Birds of a Genome

Married couples have more similar DNA than random pairs of people, a study shows.

By Jef Akst | May 21, 2014

FLICKR, TONY NGUYENWhen it comes to personalities, the old adage “opposites attract” may still hold true, but at the level of DNA, people tend to flock toward similarity, according to a study published Monday (May 19) in PNAS. In a genetic survey of 825 married couples, researchers found that spouses shared more similar DNA than randomly chosen pairs.

“We do know in some sense that people prefer genetically similar spouses because we know that people tend to date and marry within their own racial and ethnic groups,” lead researcher Benjamin Domingue of the University of Colorado’s Institute of Behavioral Science told Reuters­. “We worked really hard in this study to not just replicate that fact. We eliminated racial variability and tried to control for ethnic variability. And we still find a preference for genetically similar individuals.”

Specifically, the researchers looked at 1.7 million single nucleotide polymorphisms (SNPs) of 1,650 non-Hispanic, white men and women in their 50s, 60s, 70s, or 80s. Compared to the influence of similar educational levels, a well-established determinant of human mate choice, the preference for spouses with a similar genetic composition was about a third as strong.

How people assess and choose mates of similar genetic makeup remains unclear, Domingue noted, but it likely involves a diverse array of physical and mental preferences. “For example, people clearly care about height in picking partners,” he told Reuters. “To the extent that tall people marry other tall people, that is going to result in genetic similarity among spouses. But it is difficult to know whether height or genes is driving this decision.”

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Avatar of: James V. Kohl

James V. Kohl

Posts: 516

May 21, 2014

"Spouses, more distant relatives and close friends are sometimes found to have a compatible blood group and tissue matches to the potential recipient."

In all other species ecological variation and ecological adaptations are attibuted to nutrient-dependent pheromone-production that enables mate choice for genetic diversity vs genetic similarity via control of the physiology of reproduction. Attributing cause and effect to assortative mating instead of event-related epigenetic effects on the genomes of spouses may be another important example of pseudoscientific nonsense from population genetics. For example, I learned about the likelihood of the spousal tissue type match at least a decade ago in the context of MHC and HLA compatibility testing.

Social scientists seem more likely to consider epigenetic effects on tissue type in humans to be a function of oxytocin secretion due to works on monogamous and polygamous prairie voles that link hormones to behavior sans any consideration whatsoever for the need to tether their theories to what is known about physics, chemistry, and the conserved molecular mechanisms that link the epigenetic landscape to the physical landscape of DNA in the orgnanized genomes of species from microbes to man.

Avatar of: wctopp


Posts: 110

May 21, 2014

Some of our biggest taboos are against various forms of incest.  Almost universally incest is equated with molestation.  Certainly the negative effects of inbreeding can be seen in various closed communities, mostly religious.  I wonder where the break point would be between attraction to our own genes and inbreeding/incest?

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