Parents should have the right to see the grades of their kids if they are the ones putting up the investment, even if the kid is over 18. If children do not want their parents to see their grades after they are 18, then they need to be the ones who are footing the bill.
I do not believe that tuition paying parents have a right to see grades of children over 18, because once your 18 you are considered an adult, and no one, other then them self. Should have the right to view their personal information . As it is regulated with credit information.