A growing number of researchers are looking into the science of marriage and commitment, looking at biological factors that influence a relationship’s stability and even a person’s psychological response to flirting with a stranger, the New York Times reports. It seems some people may be more naturally prone to resist temptation, but both men and women can train themselves to stay committed. In one study, a Swedish biologist looked at 552 sets of twins to find out about how a gene relates to the body’s regulation of a bonding hormone called vasopressin, and found men who carried a variation in the gene were less likely to be married. Those who were married were more likely to have had serious marital problems. And studies from McGill University psychologist John Lydon have looked at how people in a committed relationship act when tempted. In one study, highly committed married men and women were asked to rate the attractiveness of members of the opposite sex in photos. When shown the photos again, and told they were interested in meeting them, they scored the pictures lower.