“Don’t tell mummy,” says Grandma with a cheeky wink, handing over a couple more sweets. “It’ll be our little secret.”While it doesn’t seem like a particularly insidious exchange, some experts warn that encouraging kids to keep things from their parents “crosses a line that shouldn’t be crossed”.In a video shared to TikTok, DeeDee Moore, who is the founder of More Than Grand, explained why she finds this type of exchange problematic. “Don’t be the grandparent that teaches your grandchild their first lesson in deception. Let me be clear: asking grandchildren to keep secrets from their parents crosses a line that should never be crossed,” said Moore, who is a grandparent herself.Offering the example of a grandparent giving their grandchild another cookie and asking them not to tell their parent, Moore said it “seems harmless”, but it is “never okay”.Why is it a problem?Saying “don’t tell mummy” or “don’t tell daddy” is “literally asking a child to lie to their parents”, Moore explained.“Children need to know that they can tell th