A small genetic variation may determine your longterm relationship satisfaction.

Instead of asking for your partner’s Zodiac sign, it might be time to try a more scientific question: “How long are your 5-HTTLPR alleles?”

Researchers at the University of California, Berkeley have found that a small gene variant known as the 5-HTTLPR polymorphism affects how a person deals with and is impacted by a negative emotional climate. In other words, it’s one way to figure out if your potential partner can go with the flow.

For some spouses, it’s easy to move past arguments and negativity and focus on the positives; for others, the negative can cast a shadow across the entire relationship.

Using data from a 13-year observation of married couples (taken from a larger longitudinal study), researchers identified a link between relationship fulfillment and the 5-HTTLPR polymorphism, a variant that affects serotonin transportation in the brain. Serotonin is a hormone that impacts our emotions, and it’s sometimes called the “well-being hormone.”

All humans inherit their genes from their parents, and with their genotypes come individual mutations. Everybody receives a copy of 5-HTTLPR from each parent. But researchers found that a slight difference in 5-HTTLPR allele length can produce dramatic differences in how people cope with the emotional climate.

Participants with two short 5-HTTLPR alleles were most unhappy in their marriages when there was a lot of negative emotion and happiest when there was positive emotion. Participants with mismatched allele lengths were much less affected by the emotional climate of their marriages.

Researchers were surprised how much difference a spouse’s 5-HTTLPR genotype makes in terms of the affect of emotions on marital satisfaction over the long term, says lead study author Claudia Haase, Ph.D., an assistant professor of human development and social policy at Northwestern University.

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To uncover the truth about relationship satisfaction, researchers went right to the source: married couples. More than 150 couples take part in a San Francisco-based longitudinal study that began in 1989. Every five years, couples check in with researchers to report on their marital satisfaction. Genetic material was also collected in 2009 from 125 individuals in 51 couples, as well as 23 couples in which only one spouse participated.

Researchers found that emotional climates made a much deeper impact on participants with two short 5-HTTLPR alleles, particularly in older couples.

“In our study, the link between genes, emotion, and marital satisfaction was particularly pronounced for older adults,” Haase says. She cites the head of the longitudinal study, UC Berkeley psychologist Robert W. Levenson, who says that “one explanation for this latter finding is that in late life—just as in early childhood—we are maximally susceptible to the influences of our genes.”

In the day-to-day workings of a long-term relationship, the emotional climate, or how safe, respected, and understood the partners feel is crucial.

“For people with two short alleles, a good emotional climate is very important,” Haase says. Which isn’t to say that those with mismatched alleles or long alleles should settle for less, it’s simply another way to understand how people experience marriage.

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The United States could use a little help with sustaining long-term marriages. Currently, the divorce rate is nearly 53 percent, according to the Centers for Disease Control and Prevention (CDC).

“Knowing about your spouse’s 5-HTTLPR genotype might be interesting regardless of whether a couple is happy or miserable. But the more important thing for couples, especially those who are going through trouble, would be to find ways to foster a good emotional climate in their marriage,” Haase says. If one spouse has two short alleles, a good emotional climate could make a world of a difference for his or her marital satisfaction, she says.

“Knowing that your spouse has two short alleles of 5-HTTLPR can remind you that it is really important and beneficial for your spouse to create a beneficial emotional climate in your marriage,” Haase says.

It’s not all roses and candle-lit baths (though those certainly can help). With allele knowledge comes the opportunity to set the right emotional tone for a specific couple.

“[Couples] can do this in a lot of different ways: by showing lots of affection, expressing joy, joking around, and by minimizing contempt and other negative emotions,” Haase says. While those tips seem like relationship 101, for spouses with two short alleles it can provide a huge boost for marital satisfaction.

“It’s possible that emotion-focused couples therapy and counseling approaches might be particularly important and helpful for these people,” Haase says.

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