Microtrends

I was reading a book in a library today; strange thing to do I am aware. It was about microtrends in America; meaning trends that occur randomly over a period of time. One of the most interesting parts of this book was it talked about how parents are holding their children back a year in kindergarten. They aren't doing it for social reasons, for the better development or growth of the child; the study in the book shows that upper class white Americans are holding their children back so that when they go through school they will be a year older, and in theory more mature and smarter. They want their children to feel like winners. How did they do this? By cheating the system.