Let’s be honest, no one loves us as much as our grandparents. In fact, this is so true that a new study, published in PLOS ONE, suggests that grandparents are guilty of treating their grandkids with a few too many unhealthy snacks.

The report shows not only that grandparents can have a negative effect on their grandchildren's eating habits, but also that grandparents who smoke increase their grandchildren's risk of getting cancer.

The researchers, from the MRC/CSO Social and Public Health Sciences Unit at the University of Glasgow in Scotland, produced their results by looking at data on grandparent care in 18 countries, including the US and UK, from 56 studies.

It was also noted that when children were left with their grandparents, they were less likely to play outside and get sufficient exercise.

The researchers point out that the harm they could be causing is, of course, unintentional. However, this does not remove the fact that grandparents could be damaging their grandchildren's health. 

“While the results of this review are clear that behaviour 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,” said lead author Dr Stephanie Chambers from the MRC/CSO Social and Public Health Sciences Unit.

Past research has focused primarily on how parents are sometimes responsible for their children growing up with health issues, with little research directed towards how other relatives, responsible for looking after the children from time to time, might be impacting them. 

“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 explained.

All in all, the report highlights that grandparents can have a negative effect on their grandkids' weight and overall health. 

Professor Linda Bauld, from Cancer Research UK, said that children's health can be harmed in many different ways, noting that the study at hand sheds light on the “importance or the broader family picture”.

“With both smoking and obesity being the two biggest preventable causes of cancer in the UK, it’s important for the whole family to work together,” she said.