Blame Grandma And Grandpa For Your Kid’s Bad Habits

New research confirms that grandparents have a significant impact on grandchildren, but it's not all positive.

Grandparents are generally thought to be good for grandchildren, but that may depend on just how much Nana and Papa spoil their grandkids, new research suggests. A meta-analysis published in PLOS One found that grandparents—notoriously determined to spoil their grandchildren and often clueless about modern medicine—may expose otherwise healthy children to sugary snacks and tobacco.

“While the results of this review are clear that behavior such as exposure to smoking and regularly treating children increases cancer risks as children grow into adulthood, it is also clear from the evidence that these risks are unintentional,” study co-author Stephanie Chambers of the University of Glasgow told the BBC.

Scientists have been trying to figure out the evolutionary purpose of grandparents for some time, as humans are among the only species to survive after their reproductive years have ended. While several theories have emerged to explain the phenomenon of the postmenopausal woman, the dominant theory is the Grandmother Hypothesis, which states that grandparents essentially exist to help increase the survival of grandchildren through shared resources, such as pro-bono babysitting. In the U.S. alone, 60 to 70 percent of grandparents take part in some form of childcare, research suggests. There’s also evidence that these relationships are mutually beneficial—grandparents who care for their grandkids tend to live longer lives, and grandchildren who grow up on their grandparents’ laps enjoy superior emotional development.

To find out more about how grandparents impact their grandkids, Chambers and her team analyzed 56 studies across 18 countries including the U.S., UK, Japan, and China. They excluded studies in which grandparents were the primary caretakers, and focused on those that had examined how grandparents influence children’s diets, exercise, weight gain, tobacco use, sun exposure, and alcohol consumption because all of these factors are known to increase the risk of cancer. The results reveal that grandparents who were described as “indulgent” often had negative impacts on diet, exercise, and overall weight gain of their grandchildren. Likewise, when grandparents smoked in front of grandkids (typically against parents’ wishes), children were more likely to end up as smokers themselves.

The data suggests that grandparents, many of whom provide supplemental child care to kids, are in need of more support and information. “Currently grandparents are not the focus of public health messaging targeted at parents, and in light of the evidence from this study, perhaps this is something that needs to change given the prominent role grandparents play in the lives of children,” Chambers said in a statement.

Often it’s easier for elders to take the advice of experts as opposed to their adult children, and that’s what Chambers recommends — for materials geared towards educating parents and caretakers about health best practices to be geared towards grandparents as well. Because no matter how many times parents tell Grandma that chocolate milk isn’t great, an article in her AARP magazine will really get through to her.