By Amanda MacMillan
A large part of how we relate to people emotionally may be hardwired into our DNA. A new study suggests that character traits such as being open, caring, and trusting are so strongly linked to a certain gene variation that a total stranger, simply by watching us listen to another person, may be able to guess whether we have the variation with a high degree of accuracy.
Previous studies have linked several personality traits to variations in this gene, which acts as a docking station (or receptor) for the brain chemical oxytocin-often referred to as the "love hormone" because it plays a role in social behaviors such as bonding, empathy, and anxiety.
People who have two "G" variants of this oxytocin receptor gene tend to have better social skills and higher self-esteem, research has shown. Conversely, those with at least one "A" variant tend to have a harder time dealing with stress, worse mental-health outcomes, and a greater likelihood of being autistic.
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"We've known that genotype can influence personality, but we'd only ever studied what goes on inside a person-things like behavioral states and heart-rate measurements," says Serena Rodrigues Saturn, Ph.D., a senior author of the study and an assistant professor of psychology at Oregon State University, in Corvallis. "This is the first time anyone has observed how different genotypes manifest themselves in behaviors that complete strangers can pick up on."
To explore the relationship between a person's genetics and demeanor, Rodrigues Saturn and her colleagues recruited 23 romantic couples, and videotaped them while one partner recalled and discussed a time of suffering in their lives. The other partner, who had given a saliva sample to determine his or her genotype, was simply asked to sit and listen.
The researchers then showed 20 seconds of each video clip to a group of 116 people. None of the viewers knew the video subjects, and they watched the clips with the sound off so they had no knowledge of the situations being discussed. They were then asked to rate how kind, caring, and trustworthy the listening partner seemed, based only on visual cues.
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"They looked for things like nodding along with their partner, holding eye contact, keeping an open body posture," Rodrigues Saturn says. "Those people were judged as more social and caring, as opposed to others who seemed much more aloof."
Although they expected to find some association between the subjects' genotypes and their rankings, the researchers were "blown away" by how accurate the observers' intuition actually was, Rodrigues Saturn says. Out of the 10 people who were ranked as "most prosocial," six had the GG genotype, and of the 10 ranked "least trusted," nine were carriers of at least one A variant.
The findings were published today in the Proceedings of the National Academy of Sciences.
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Keith Kendrick, Ph.D., a neuroscientist at the University of Electronic Science and Technology of China, in Chengdu, says it's important to note that genes besides the oxytocin receptor gene-not to mention other, non-genetic factors-influence social behavior as well. Oxytocin receptors have been shown to be modified by a person's environment, for example, so life experiences presumably play a large role too, he says.
"Just because you have an 'A' version of this one receptor gene clearly does not mark you down as a completely unsocial individual," says Kendrick, who was not involved in the study. "Obviously many different genes contribute to something as complex as social behavior, but it is interesting that this particular one appears to be so influential."
One genotype isn't necessarily better or healthier than the other, Rodrigues Saturn says. Although scientists used to refer to the gene's "A" variant as a "risk" variant (because it increases risk of autism and social dysfunction), many experts now think of the variations as just that: variations that may-along with many other forces-play out in personalities.
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"It's important to understand that some people are…naturally more held back, or may be overcome by their own personal stresses and have a hard time relating to others," Rodrigues Saturn says. Putting these people in more comfortable environments that naturally induce the production of oxytocin may help to coax them out of their shells and help them feel more "warm and fuzzy," she says.