Knowledge is power.
But these days there are no combined families and wife, husband and their children are their families. No grandparent is staying with them. So there may not be much difference. Who visit them frequently and whom they visit frequently will decide the attachment of the grandchildren with their grandparents.
Another factor is the nature of the grandparents. Some grandparents may not be sparing much time for spending with their grandchildren. In such a case, grandchildren can't get the required attachment with their grandparents.