Not only do sleigh bells ring in December, but wedding bells ring, too. According to the wedding experts at The Knot and The Wedding Channel, December is the top month for engagements. But what if the happiness of your marriage could be predicted by something as subtle as a gene you were born with? According to new research, the secret to a happy marriage may actually be in your genes.

Researchers from the University of California at Berkeley have found a gene that affects the regulation of serotonin in the body and can predict how much emotion can affect relationships. The team found a link between relationship happiness and fulfillment and a harmless variation in that gene.

Everyone inherits two versions of genetic information, one from each parent. Sometimes harmless variations, or alleles, occur in these genes. In this study, participants who were born with two short versions of the 5-H-T-T-L-P-R alleles were found to be the unhappiest in their marriages when there was a lot of negative emotion and happiest when there was a lot of positive emotion. But people with long alleles were not as bothered by the emotional ups and downs of their marriages.

The study looked at 100 married people, examining their genotypes and observing their relationship with their partner over the course of 13 years. The researchers say emotion is an important ingredient in all the relationships.

Worried your genes may have you headed to divorce court before you’ve even walked down the aisle? Fear not … the research does not mean that people who have short 5-H-T-T-L-P-R alleles are doomed to suffer through a failed marriage. Rather, what it does seem to indicate is that those who have two short alleles on both sides are more likely to thrive in a good marriage and hurt in a bad one.