Question:  A recent sociometric study on obesity (similar to the one we read about regarding clusters of smokers) provides a striking example of how our social networks influence what we do. The researchers analyzed a sample of more than 12,000 people who participated in the Framingham Heart Study, which closely documented their health from 1971 to 2003. They discovered that obesity can spread from person to person, much like a virus. The investigators knew who was friends with whom, as well as who was a spouse or sibling or neighbor, and they knew how much each person weighed at various times over three decades so they could reconstruct what happened over the years if study participants became obese. Guess what? When one person gains weight, close friends tend to gain weight, too. A person's chances of becoming obese if a close friend put on the pounds increased by 57 percent! The friend's influence remained even if he or she lived hundreds of miles away. The researchers speculated that the reason for this social contagion effect is that when our best buds get fat, this alters our perception of normal body weight so we aren't as concerned when we put on a few pounds as well. How does social contagion work in your life?