Each person has 2 biological parents and 4 biological grandparents.
If we assume that the average age of becoming a parent is 25 years old, over 100 years 4 generations would be born and a total of 16 great-grandparents (2 times).
For Christimas this year, my husband framed a beautiful copy of my family tree showing the last 5 generations. 32 great-grandparents. There's still some holes, but 32 family surnames is a lot to track and master.
But if I set my goal to understand the last 500 years of my families' histories I would need to document 1,048,576 great-grandparents (17 times). Well, that feels overwhelming! Makes my 10,000 persons accomplishment seem so miniculse.
