A Reason for the Generation Gap?

If John McCain fails in his bid to become the next President of the United States, it is almost certain that there will never be a U.S. President born during the Great Depression. In fact, no Presidents were born in the 22 years between 1924 (George H.W. Bush and Jimmy Carter were both born during that year) and 1946 (Bill Clinton and George W. Bush). Given that someone born in 1945 would be 67 in 2012, it almost certain that we will not ever elect a President within that time frame.

There is no comparable period in American history. The closest was the period from 1890 to 1908, but that is partly explained by the 4 term presidency of Franklin Delano Roosevelt. Had FDR joined all of his predecessors by bowing out after a maximum of two terms, it is almost certain that one of his successors would have come from that period.

This brings forth a question: is the absence of Presidents born during that time frame dominated by the Depression and World War II a historical anomaly, or is there some sociological significance?

I have a theory that I may put forth later. It requires some work.