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Here’s a fun primer on deep genealogy….

Okay… so we have two parents, four grandparents, eight great-grandparents and sixteen great-greats… but few people think beyond those 3 or 4 generations of ancestors closest to us and whose pictures might be found while dusting in the attic.  In short, every generation doubles the number of ancestors, across the board and without exception.

  • 1st generation — 2 parents
  • 2nd generation — 4 grandparents
  • 3rd generation — 8 great-grandparents
  • 4th generation — 16 great-greats
  • 5th generation — 32 great-great-greats
  • 6th generation — 64 great-great-great-greats

After 32 “great-great-greats” and 64 “great-great-great-greats” the number really accelerates.  By the 10th generation there are 1024 direct ancestors mixed into your DNA, and by the 15th generation, 32,768.  By the 20th you cross the million ancestor mark at 1,048,576 and are looking for a bigger house just to display the family album… by the 30th 1,073,741,824 and by the 40th generation a staggering 1,099,511,627,776 grandmas & grandpas (Yes, for the record, that’s a TRILLION… it’s a lot of cards and anniversaries to keep track of… and a lot of grudges against you should you forget).

But here’s the paradox: the further back in time the smaller the ancestral pool.  In other words… one trillion is impossible without some serious genealogical overlap.

Given that this journey through 40 generations of time takes us back to the 9th Century (+/- several decades) — a time when the world population hovered near 250 million and the European population is estimated on the generous side at 30 million — it is safe to say that everyone in the Western World who is derived from any European or Scandinavian stock is descended from EACH and EVERY successful child-bearing line of 9th Century Europe — and not just once… but on average, 36,650 times over.  (And this number is in fact, ridiculously conservative, in that 30 million represents the entire population, not just successful child bearing lines.)  Some ancestors would be represented more often while others less, but regional and cultural isolation (Jewish enclaves, Moors in Spain) offers no exception to the rule… all it takes is one ancestor, a “gateway grandpa” to bridge the narrow into every nook & cranny in the genealogical atlas.  In the end, the odds average out to 36,651 to 1 that you are NOT directly descended from every man & woman who walked European soil in 800 AD and who happened to have a child, who had a child, who had a child….