We are probably several centuries out. Thought experiment - how many generations does it take to forget grandpa? If Grandpa is the issue, their grandchildren

We are probably several centuries out. Thought experiment - how many generations does it take to forget grandpa? If Grandpa is the issue, their grandchildren may have falsely optimistic opinions of their corrupt roots. Their children (grand grand children) don't have the same rosy memories, and don't get why Mom and Dad are into their weird rituals. But it's Mom and Dad so it can't be so bad, right? It's not till their grandchildren, normally, that (assuming they are decent people and the trait isn't genetic or somehow encouraged by society) people can maybe see what utter crappy people their grand grand grand grand parents were, and maybe do something about it.