The drinking habits of the people in your extended social group play a major role in determining how many adult beverages you consume, says researchers writing in the Annals of Internal Medicine.

The authors suggest this social phenomenon could have implications for clinical and health interventions. Social networks could be used to exploit positive health behaviors and further support group interventions.

In the study, self-reported alcohol intake over time followed changes in the alcohol intake of the respondents' social contacts. The researchers found that a person was 50 percent more likely to drink heavily if a person they are directly connected with also drinks heavily and 36 percent more likely to drink heavily if a friend of a friend drinks heavily. The impact extended up to three degrees of separation.

Researchers used data from the Framingham Heart Study, which followed 12,067 people for more than 30 years and helped to define the patterns in social networks of other health issues such as obesity, smoking, and sexually transmitted diseases.

"We've found that the influence of your friends and people you have connections with can affect your health just as much as your family history or your genetic background," said Nicholas Christakis, MD, PhD, Professor of Medicine at Harvard University and lead author of the study. "With regard to alcohol consumption, your social network may have both positive and negative health consequences, depending on the circumstances."

Citation: Rosenquist et al., 'The Spread of Alcohol Consumption Behavior in a Large Social Network', Ann Intern Med, April 2010, 152:426-433