Married couples typically have a lot in common and researchers now say that may extend to their genes

Spouses tend to be more genetically similar than two people chosen off the street at random, according to a new study. It's likely this is because people who are genetically similar have more opportunities to meet and mate - in other words, "birds of a feather flock together," said lead author Benjamin Domingue, a research associate at the University of Colorado-Boulder's Institute of Behavioral Science. "Genes drive so many things that can structure opportunities and outcomes that determine who we mate," Domingue said. For example, genes may determine whether your potential partner shares your height or weight, or your ethnic background, religion or level of education. Domingue and his colleagues examined the genetics of 825 white heterosexual American married couples, comparing 1.7 million potential points of genetic similarity. The results found that spouses share a significant number of genetic similarities, compared to any two random individuals. This conclusion could end up changing the statistical models scientists use to understand genetic differences between human populations, because such models often assume random mating, the researchers said. Married couples likely have similar genetic traits because their genes helped determine whom they would meet during their lives, Domingue said. "People with more similar genes end up having similar education, which places them in the same social situations and gives them a better chance to mate," he said. People also tend to marry those similar to themselves in terms of race, ethnicity and even body size and shape. Genes may also shape even more subtle biological distinctions that draw people together in ways we don't yet understand, Domingue added.