Once I was diagramming family trees while waiting for Lizzie to finish at Publix. It's amazing how complex they grow over just 3 or 4 generations into the past, or into the future. It's like a tree: you are now, the trunk. Below, in the past, are the roots: your parents, grand parents, etc. Above is the future: your children, grand children, etc.
I would like to understand how the roots grow ever bigger below into small rootlets, yet all reach back to a single couple: Adam and Eve. Even if you hate the idea of God and creation, it still reduces down that way: to a single couple, or at least a very few couples.