PS, John, I don't think it's that the information wasn't out there - e.g., about Maureen and Michael not being Nancy's kids - as much as that it didn't get much prominence in press coverage. And that was especially true on stations and channels that lean to the right in their coverage (e.g., Fox).   

There's many a fact that occasionally gets cited somewhere - maybe in passing - in the newspaper or in a radio or TV broadcast but which barely pierces the collective consciousness or is forgotten almost as soon as it's received.