Grandparents are more likely to give their grandchildren too much food and allow them to skip exercise, according to a study carried out by researchers at the University of Glasgow.
The research found the older generation are also more likely to give children sweet treats and ignore warnings about the harmful effects of second-hand smoke.
The study, published in the journal PLOS ONE, concluded many grandparents around the UK may “inadvertently” be damaging the health of their grandchildren.
Smoking, a poor diet and a lack of physical activity were all been identified as risk factors for diseases such as cancer, which children may carry into adulthood.
The Glasgow team analysed data from 56 studies from 18 countries that included information about the influence of grandparents on their grandchildren. Grandparents overall were found to have an adverse effect on the health of the children despite meaning well. The research found “excessive feeding” of children was a significant grandparent problem, as was providing meals made from unhealthy ingredients.
Sweets were also often used to reward, express love or strengthen the bond between grandparent and child.
There was also evidence the poverty and hunger some grandparents experienced themselves as children led them to believe extra weight was a sign of good health.
None of the reviewed studies took into account the positive emotional benefit of children spending time with their grandparents, the authors said.
Lead author Dr Stephanie Chambers said. “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.
“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.”
Previous research has studied the way parents can affect their children’s susceptibility to cancer and other diseases, but less attention has been paid to the role of part-time carers.
The authors also pointed out more children were being placed in the care of their grandparents due to a variety of social trends.
These included the growing proportion of women in the workforce, rising childcare costs and increasing numbers of single parents.
Tam Fry, chairman of the National Obesity Forum, said it was the case that some grandparents “bring out the biscuits at the slightest hint of a tantrum”.
“Finding a doting grandparent who is confident enough to follow rules laid down by mum and dad to the letter is frequently a rarity,” he said.