Each one of us descends from 4 Grand Parents:?

Question:

Each one of us descends from 4 Grand Parents:?

(2 Grand Fathers and 2 Grand Mothers). However, if it were possible somehow to trace them all, how many blood ancestors would we find if we went back 80 generations ? (please assume 25 years between each generation).

Best Answer - Chosen by Asker: I'm French and have many, many grandparents who are repeated. Are we supposed to count them more than once? I descend from Xaintes Dupont and Zacharie Cloutier 16 times. Do I count them once or all 16 times?

Question much more complicated in real life than it is in statistics class. But in 30 generations you have more than 25,000 ancestors. So keep doing the math, but I don't personally believe the population of Europe was sufficient that each of us descends from 25000 unique individuals over those 30 generations.