qqp question1: If I follow the logic that I have 2 parents, 4 grandparents, 8 great grandparents etc. and a generation equals 25 years; then after 37 generations, or 925 years ago, I should have a family tree with over 130 billion people, more than all the humans that have ever lived. How is this possible? question2: Does grandchildren/grandparents relationship exist in any other living beings than humans?