Researchers have identified a new culprit in the epidemic of childhood obesity: parents who can’t even tell that their pudgy kids are overweight.

A new study in the journal Pediatrics finds that American parents are significantly less likely to make an accurate assessment of their children’s weight compared with parents from an earlier generation. If moms and dads don’t see the problem, they aren’t likely to be part of the solution, the researchers say.

“Crucial to parental involvement in weight reduction or maintenance efforts among children is parental recognition of their child’s overweight status,” the team wrote in the study, which was published Monday. “This recognition and the associated health risks are the main driving force motivating parents to take action.”

The Centers for Disease Control and Prevention define childhood obesity not according to body mass index (as it does for adults) but according to how a child’s BMI compares with that of other kids of the same age and gender.

Children who have a BMI at or above the 95th percentile are considered obese, and those with a BMI between the 85th and 95th percentiles are considered overweight. In 2012, fully 18 percent of children between the ages of 6 and 11 were considered obese, up from 7 percent in 1980, the study authors wrote.