Q: Is obesity contagious?

Researchers studied 1,519 military families who were assigned to 38 military bases across the country and living in counties with higher or lower rates of obesity.

The scientists collected data on height and weight of children and parents using questionnaires and in-person examinations.

The study, in JAMA Pediatrics, used data on county obesity prevalence from the federal Centers for Disease Control and Prevention.

County obesity rates ranged from 21 percent to 38 percent, and each percentage point increase in obesity was associated with a 5 percent higher rate of obesity in military parents and a 4 percent higher rate in their 12- or 13-year-old child.

The researchers controlled for many variables, including age, sex, race, education level, income and “built environment,” that is, whether a county had easily accessible exercise opportunities, good supermarkets and so on.

“Subconsciously, you are affected by what people around you are doing,” said the lead author, Ashlesha Datar, an economist at the University of Southern California, adding, “If you move to a community where a sedentary lifestyle is the norm, you join that. There is this social influence.”