Those who were considered to be most trustworthy were similar genetically in terms of the single gene. The same was true for those who were deemed least trustworthy -- they were similar to one another, but in a different way.
People with the "kindness" gene showed more empathetic behaviors, like nodding their heads, smiling and making eye contact than people with the other type of gene.
The question now is: If these links aren't a coincidence, how are genes affecting how empathetic people appear to be to others? Could it affect their behavior? The way their faces look? Something else?
In the big picture, the research could lead to better understanding of why some people are kind and others aren't, Kogan said. It could even lead to insight into why some people are psychopaths.
Paul Zak, a brain researcher and founding director of the Center for Neuroeconomics Studies at Claremont Graduate University, in California, said the research is interesting but not yet world-changing.
"Some people would say there is now a gene for being nice to other people. That's not true at all," he said. Many other genes matter, too, he said, as do more important factors like your current physical state and your personal history.
In other words, if you're a jerk or a saint, your genes shouldn't get all the credit -- or blame.
The study appears online in this week's issue of the Proceedings of the National Academy of Sciences.
The U.S. National Library of Medicine has more about genes.
SOURCES: Aleksandr Kogan, Ph.D., postdoctoral fellow, psychology, University of Toronto, Canada; Paul Zak, Ph.D., chair and professor of economics, and founding director, Center for Neuroeconomics Studies, Claremont Graduate University, Claremont, C
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