Researchers in the USA may have come up with some of the first evidence linking genes, emotion and marital satisfaction.
Their study, published in the journal Emotion, investigated over 150 middle-aged and older married couples. These couples have been followed since 1989 as part of a larger longitudinal study.
Senior author Professor Robert Levenson, from University of California (UC) Berkeley said he was investigating 'an enduring mystery - what makes one spouse so attuned to the emotional climate in a marriage, and another so oblivious?'
Couples in the study went to the UC Berkeley campus every five years and interacted in a lab where their conversations, facial expressions, body language, and tone of voice were recorded. The scientists then analysed this data, together with participants' genetic information and results from marital satisfaction surveys.
Their results centred on the influence of variants of the 5-HTTLPR gene. 5-HTTLPR is involved in transmission of serotonin, a neurotransmitter that is important in regulating emotion. People inherit either a long or short version - or 'allele' - of this gene from each parent.
The study found that depending on the combination of the 5-HTTLPR alleles, participants were differently affected by the emotional climate of their relationships. Participants with two short alleles (17 percent of participants) were more negatively affected by the ups and downs of their marriage, whereas people with one or two long alleles (83 percent) could more easily cope.
Researchers identified a strong correlation between the emotional tone of participants' conversations, their genotype, and how they felt about their marriage. This link was even more pronounced for older couples.
'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', Professor Levenson suggests.
The researchers note that no allele combination is inherently good or bad. The study's findings suggest that people with two short alleles are happier in relationships under ideal circumstances, but are more likely to suffer when problems arise.
Whether or not such genotype combinations play a role in couples getting together in the first place is open to debate. However, one recently popular theory on why humans frequently kiss, suggests that it might be a method to assess the genotype of their partners from clues like taste and smell.