Ask a long-married couple what the secret to all those years of domestic bliss is and they'll probably put you to sleep with platitudes: honesty, communication, "never go to bed angry!" and some rubbish about doing the dishes.

But if you really want to know what keeps a marriage together, kindly ask them to undergo genetic testing.

Because the ace up their sleeve may be in their genes.

At least, that's what new research from the Yale School of Public Health suggests. Published this month in the journal PLOS One, the study focuses on 178 married couples ranging in age from 37 to 90 years old. After gauging the degree of each couple's marital bliss through a series of questions — and collecting a little spit — the researchers zeroed in on a common strand shared by the most satisfied spouses: a genetic variation known as the GG genotype within the oxytocin gene receptor.

Or, if you want to get short and science-y, OXTR rs53576.

The Yale researchers noted that couples who reported the most joy in their union simply had more of it — at least in one, if not both spouses — than those poor souls who had to go of marriage without a genetic cheat sheet.

"This study shows that how we feel in our close relationships is influenced by more than just our shared experiences with our partners over time," lead author Joan Monin explained in a press release. "In marriage, people are also influenced by their own and their partner's genetic predispositions."

This may, of course, be just what you want to hear. Never mind all that claptrap about hard work and shared values. Some people are just naturals at this whole marriage thing.

Now, bring on the OXTR rs53576 smoothies. Let's make marriage great again!

Or, not.

You see, researchers noted that an individual's GG genotype and their partner's GG genotype together account for about 4 percent of the variance of marital satisfaction.

Illustration of couple in bed using phones. Genes alone can't save a marriage from the stresses of real life. (Photo: jesadaphorn/Shutterstock)

In other words, that percentage may be a natural advantage, but couples have to survive a gauntlet of other real-world stresses — not to mention other genetic factors, like a natural aversion to doing the dishes.

And, of course, OXTR rs53576 isn't specifically designed to make you the perfect spouse-bot. Rather, researchers found the genotype was linked to qualities that make us better humans in general: emotional stability, empathy and sociability.

About that 'anxious attachment'

What it's particularly good at on the marital realm, however, is making a partner a little less annoyingly clingy. Researchers call it "anxious attachment" — a kind of relationship insecurity we pick up from past, negative experiences with family and loved ones. It results in feelings of low self worth, painful sensitivity to rejection and constant need for approval.

As you can imagine, that's not the stuff of successful marriages, but rather relationships that are doomed to fail — and amplify that behavior along the way.

OXTR rs53576, on the other hand, may play a role in smoothing over anxious attachment and, if not exactly promising eternal sunshine, at least reducing the risk that one spouse will feel that she married a giant, blithering baby.

In fact, researcher note in the study, the opposite of anxious attachment is attachment security — which "plays an essential role in effective communication, problem solving, and social support and it is a strong predictor of marital satisfaction over time."

Man holding a rose and a ring behind his back before proposing. If OXTR rs53576 and marriage go together like a horse and carriage, maybe potential couples should be screened for it in advance. (Photo: May_Chanikran/Shutterstock)

So the next time that old married couple is preening on about honesty, respecting each other's needs and blanket sharing, you may cut them off with a knowing wink: Genes.

And maybe even ask them to show a little bit of that much-vaunted empathy for the luckless souls who missed the OXTR rs53576 boat and have to work a little harder for their marital bliss.

Now, would you please take out the trash and clean the garage already?

Scientists may have found the gene that makes a marriage stick
New research suggests long, happy marriages may be in the genes.