Question 65876
<b><font size = 6>The one about the number of people when counting yourself through your great grandparents using 40 "greats".  Since the number obtained is roughly 1000 times the number of people that have ever lived, this is absurd.  There must be something wrong with the reasoning. What is it?
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The explanation is that people inevitably marry their distant cousins, so that most positions far up in an ancestral tree are not filled by distinct people.
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Edwin</b>