I googled the amount of people that lived on earth throughout its entire history, it’s roughly 108 billions. If I take 1 person and multiply by 2 for each generation of ancestors, at the 37th generation it already outnumbers that 108 billions. (it’s 137 billions). If we take 20 years for 1 generation, it’s only 740 years by the 37th generation.
How??
(I suck at math, I recounted it like 20 times, got that 137 billions at 37th, 38th and 39th generation, so forgive me if it’s not actually at 37th, but it’s still no more than 800 years back in history)
In: 1391
You assume that every one of your ancestors is only related to you in one way, that is an incorrect assumption.
A simple example is if your parent was siblings. Then there are only two instead of 4 people two generations back. The rest of the ancestor tree now gets halved.
Siblings having children is not common, it is just a simple example to show that the ancestor tree can collapse in size. Globally it is not uncommon that cousins to get married. Worldwide 10% of all marriages are between first or second cousins.
The more generation you go back the more likely it is that two persons that have children have a common ancestor. Do you know who your ancestors are 5 generations back? If your parents are from families that have lived in the same relativity small location for a long time I would say it is likely you find common ancestors not that far back.
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