I picked up that statistic in an essay contained within Changing the World of Work by Marjorie Ford. I can't recall which specific essay. I don't believe the study listed its paremeters either. Unfortunately, almost no study does. While I do not profess to believe everything I read, I would agree with the 1% number of a number very close to it. While at certain points in your life your economic class will change, I believe that you ultimately will be right about where your parents are financially. I apologize I can't do better on the reference. If I find the book, I'll find the specific essay and author.