Love at first DNA match? Marriages likely based on gene similarities

When choosing your life partner, you may find yourself pondering a number of questions: do you both have the same level of education? Do you have the same basic attitudes and beliefs about religion? Do both of you have similar feelings on having or not having children? Are you relatively clear on how much time you would like to spend with family? Although these are key questions to ask yourself before deciding on your spouse, according to one study there is more to it than you think.

According to the new study “Genetic and educational assortative mating among U.S. adults,” which was published in May, people are more likely to pick spouses who have similar DNA to theirs. It turns out that the old “opposites attract” adage isn’t really true!

Birds of a feather flock together

Instead, it was found that that people marry spouses who are genetically similar to them, which supports the other adage that goes “birds of a feather flock together.” The study, which was published in the journal Proceedings of the National Academy of Sciences, is the first of its kind to actually study the genome of married couples. According to the findings, individuals were found to be more genetically similar to their spouses than they are to randomly selected individuals from the same population.

Researchers examined the DNA building blocks of 825 white heterosexual married couples in the United States born between the 1930s and 1950s and found a significant preference for a spouse with DNA similarities across the entire human genome. For example, people tend to care about height when choosing partners. So when tall people prefer marrying tall people that is going to result in genetic similarity. The question is however, is it your height or your genes that are driving you to make these subconscious decisions?

The study also revealed that couples who share an increase in genetic similarity by one standard deviation are 15 percent more likely to getting married.

Why does this happen?

It’s not clear why this happens but the researchers in this study talked about three possible explanations: birth region, ethnicity and education. People born in the same geographical area are more likely to marry partners with a similar genetic profile, which birth region in turn extends to ethnicity. As a result, the researchers decided to control for both birth region and ethnicity and still found a high amount of genetic similarity between couples. They believe that part of the explanation for the results is level of education. People tend to look for partners with the same educational background, and this has been found to be somewhat tied to genetic makeup. But part of the mystery still remains unsolved.

“On an academic level, I think it is important since it challenges some of the assumptions of key statistical genetic models and furthers our understanding of spousal similarity”, the study author Benjamin Domingue from the University of Colorado Boulder told Al Arabiya News. The study also built a foundation for future studies involving other populations including additional races and interracial spouses. When asked if they will conduct follow up studies, Domingue said: “they will probably go in different directions” by first looking at other areas of the genome other than DNA, such as chromosomes. They would also like to evaluate whether people are also likely to choose friends with similar genes as well.