I'm grandparent age myself now, but I know that despite being respected members of the community my own parents kept their children alive til adulthood more by luck than judgement.
An examples that I was old enough to remember clearly from my own childhood is that as a 7 year old I had the "job" of supervising younger siblings including a toddler in a garden with a large unfenced fish pond every afternoon after school, while my mum got changed out of her work suit and then cooked dinner indoors (father usually still at work) - no window from the kitchen onto the garden where the pond was, it was behind a different part of the house, for example.
My mother casually suggested leaving one of my children in the pram in the garage overnight as a baby because she didn't sleep well (my mother was staying with me and was woken by the baby and me going to the baby during the night). She casually told me that she did that with one of my siblings - so the family could all get some sleep. She went on to claim she did it for me, as I was five and needed to get a good night's sleep for school, when I expressed horror. She also had an eating disorder (which she continues to suffer from in very old age now) and always behaved very strangely around food - we wouldn't have starved but she was very restrictive and alternated forcing us to eat food we didn't want with withholding food - one sibling as a teenager was in an adolescent psychiatric unit due to anorexia and lucky to survive, another had bulimia. My mother's main concern was telling people who asked after my sibling that it wasn't her (my mother's) fault. Father was a workoholic who lived in the house but left our mother to raise us, if he was around he just looked up from his newspaper/ journal or away from the TV to back her up with whatever she did or said.)
She pulled a lot of the same nonsense with my brother's children, down to offering to babysit and then leaving his year 2 child in the (same) garden, with the same unfenced and uncovered fish pond babysitting his preschool brother - when DN2 fell in he was luckily fished out by their gardner - my dad's response was to blame DN1 "I wouldn't be surprised if the little bugger pushed him in" were his words.
But yeah - grandparents are automatically perfect as long as they didn't actually have their children removed by social services... "You survived didn't you" - yes, more by luck than judgement.