For one of us to be born, it took:
2 parents
4 grandparents
8 great-grandparents
16 great-great-grandparents
32 third-great-grandparents
64 fourth-great-grandparents
128 fifth-great-grandparents
256 sixth-great-grandparents
512 seventh-great-grandparents
1,024 eighth-great-grandparents
2,048 ninth-great-grandparents
In only the last 11 generations, that’s 4,094 ancestors—roughly within the 300 years before you or I were born!
And, if you go back 33 generations, or about 1,500 years, we all have 1 billion direct ancestors, and each additional further generation doubles it