A new study in Journal of Personality shows that selfless and social behavior is not purely a product of environment, specifically religious environment. After studying the behavior of adult twins, researchers found that, while altruistic behavior and religiousness tended to appear together, the correlation was due to both environmental and genetic factors.

According to study author Laura Koenig, the popular idea that religious individuals are more social and giving because of the behavioral mandates set for them is incorrect. "This study shows that religiousness occurs with these behaviors also because there are genes that predispose them to it."

"There is, of course, no specific gene for religiousness, but individuals do have biological predispositions to behave in certain ways," says Koenig. "The use of twins in the current study allowed for an investigation of the genetic and environmental influences on this type of behavior."

This research is another example of the way that genes have an impact on behavior. "Society as a whole assumes that home environments have large impacts on behavior, but studies in behavior genetics are repeatedly showing that our behavior is also influenced by our genes," says Koenig.