Serotonin Gene Impacts Response To Moral Dilemas

A new study, described here, shows that people with different versions of a gene related to the way the brain handles the neurochemical serotonin (5-HTTLPR) evaluate moral dilemas differently, even though the gene didn't have an impact on moral evaluations of unambiguous situations. People with two short versions of the gene tended to respond to situations emotionally, those with two long versions of the gene tended to favor utilitarian greatest good for the greatest number resolutions, and those with one of each tended to come out in between the other genotypes. People on SSRI (selective seretonin reuptake inhabitors) drugs exhibit changes in their moral judgments (also here) similar to those caused by a difference in this genotype. Other genes that influence serotonin, such as the MAOA gene also appear to influence behavior on a similar dimension.

Note that it isn't clear that one or the other version is "better" overall. Consider the following abstract:

Converging evidence suggests that the short allele of the serotonin transporter gene polymorphism increases risk for a variety of psychological disorders, including depression, anxiety, and alcoholism. Thus, the short allele is typically considered the “risk” allele, and findings related to the long allele are rarely discussed.

However, upon closer examination, findings associated with the long allele of the serotonin transporter gene share striking similarities with findings from studies of psychopathy. Here, the parallels between findings associated with the long/long genotype and findings associated with psychopathic traits in the areas of neuropsychology, psychophysiology, hormones, and brain imaging are reviewed. It is suggested that the long/long genotype may be a potential risk factor for the development of psychopathic traits.

Andrea L. Glenn , "The other allele: Exploring the long allele of the serotonin transporter gene as a potential risk factor for psychopathy: A review of the parallels in findings," Neuroscience & Biobehavioral Reviews Volume 35, Issue 3, January 2011, Pages 612-620 doi:10.1016/j.neubiorev.2010.07.005