Serotonin Receptor (HTR2A) Gene Polymorphism Modulates Social Sharing of Happiness in Both American and Japanese Adults

A single nucleotide polymorphism in the serotonin 2A receptor gene (HTR2A rs6311 guanine [G] vs. adenine [A]) appears associated with positive emotional contagion (social sharing of happiness) in Japanese people. However, it remains unknown whether the HTR2A polymorphism also impacts the social sharing of happiness in Western cultures. The present study thus compared 207 Japanese university students and 200 American adults (including non-students). Social sharing of happiness was examined using a vignette-based questionnaire. Participants were asked to imagine that they were experiencing an emotionally neutral event. At the same time, they were asked to imagine that a friend was experiencing a positive valence event (presence condition), whereas in the other condition such information was not presented (absence condition). Results showed that the G allele carriers felt happier in the presence than in the absence of the friend compared with participants with the AA genotype. Although we did not specifically consider comparability between the two samples, the findings suggest that the effect of HTR2A polymorphisms on social sharing of happiness observed in Japanese populations may be applicable to American populations.