Why are some people content in their marriages while their partners are not? Why do some people feel dissatisfied with marriage or relationships in general? Scientists at the University of California - Berkeley, believe marital happiness may be linked to our genes.
We inherit an 5-HTTLPR allele - a gene variant - from our parents. There are short alleles and long alleles. A recent study showed that those with short alleles are more likely to be dissatisfied with their marriage than those with long alleles.
The researchers followed 156 couples since 1989. Every five years the couples met with researchers, assessed their marital satisfaction and interacted with one another in a lab, where the scientists could observe the interactions, looking at facial expressions, body language, tone of voice and topic of conversation. A majority of the couples, 125, recently gave DNA samples.
The researchers looked at the 5-HTTLPR allele and found that those with two short alleles were "most unhappy in their marriage when there was a lot of negative emotion and most happy when there was a positive emotion." Those with long alleles did not indicate a correlation between marital satisfaction and the current emotion. Some people, it seems, are more sensitive to the emotional current than others.
It is important to note, according to the scientists, that one is not "better" than the other or that couples aren't compatible if they have different types of these alleles. However, those with two short alleles "are more likely to blossom in a good relationship and wither in a bad one." 
Interestingly, older adults showed a stronger link between the alleles and marital satisfaction, "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,"  according to Professor Levenson, lead author of the study.
While this study can't help you pick a partner, it can help to explain why some people are more sensitive to the emotional climate in their relationship and why satisfaction continues to change - during happy times both partners are satisfied but during periods of your relationship when things aren't going so well, one or both partners may feel less satisfied.
  "Marital Satisfaction Linked to Genetic Variations," 2013, Oct. 11, Marie Ellis, Medical News Today