08-21-2013, 08:14 PM
Would depend much on the part of the country. In some areas of the south (and this is not to dis the south, they were different times), a generation was as little as 15 years. The average for the longest time was 20 years. So, one's great great grandfather could be still be alive today, given the current trend toward longevity: many folks are living past 100 years these days.