Divorce spreads like contagion

People who have a divorced friend are three times more likely to get divorced themselves, according to a new Yale study.

Through analyzing an existing data set of 5,000 people from Framingham, Mass., researchers found divorce may be contagious among friend groups. Not only can divorcees be found in the same social circles, but they can also influence their friends’ likelihood of divorcing. This finding has implications for understanding how a range of social phenomena spread, said director of Yale’s Human Nature Lab and study senior author Nicholas Christakis ’84.

“Humans are copycats, and we copy each other in all kinds of ways,” Christakis said. “We’ll copy each other when it comes to drug use and bank robbery, and equally when it comes to marital stability and cooperation.”

The idea for the study came when Rose McDermott, the study’s lead author and professor of political science at Brown, noticed that many people she knew were getting divorced at the same time as she was, McDermott said in an email to the News. This led her to suspect that people whose friends divorce are themselves more likely to divorce as well.

The researchers found that effects of divorce extend to two degrees of separation — the divorce of a friend’s friend can affect one’s own marriage — and that people who have a friend who is previously divorced are 270 percent more likely to get divorced themselves.

The study also investigated the degree of contagion involved with different types of relationships. The health of the marriages of one’s friends, the authors found, is more important than the marriages of one’s siblings, neighbors or co-workers, Christakis said, but the study was unable to conclude why this effect exists.

Christakis said multiple factors may cause divorce to spread in social circles, including divorced friends showing that life after divorce may be better, or an environmental or social factor that affects the entire group.

“I think we need to know a lot more about how and why these effects happen,” McDermott said. “We can show that they happen but we can only speculate as to why with the data we have.”

Previous studies had explored the effects of social environments on relationships — for example, how the number of friends a couple shares affects their marriage — but not the opposite direction: how relationships affect social networks. In addition, person-to-person effects of divorce had been studied, but not person-to-person-to-person, the authors wrote in the study.

The findings open multiple avenues for future research, sociology professor Emily Erikson said in an email to the News. The idea that social context influences people’s patterns of behavior is not new, she said, but breaking down a pattern like divorce into elements like network ties is what makes this research particularly interesting. In the future, Erikson said other elements like cultural norms could be investigated as factors contributing to the spread of divorce.

“I think we need to realize that any kind of social policy has network effects,” Christakis said. “Social networks magnify whatever they are seeded with. If we have policies in place that encourage or discourage divorce, social networks will make them have a bigger impact than they otherwise would.”

Attention for the study itself may have been magnified when it appeared as number three on Stephen Colbert’s ThreatDown, the talk show host’s recurring countdown of what he views as the greatest threats to America.

“The real threat to marriage is threat number three: divorce. Didn’t see that one coming, did you?” Colbert said in his Oct. 30 segment.

“I adore [Colbert],” McDermott said. “[Having him mention my research] was one of my ultimate life dreams coming true. Nothing could have made me happier. It was the one thing that made all the work worthwhile.”

According to the American Psychological Association, 40 to 50 percent of marriages in the United States end in divorce.

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