We are all descendants of Adam and Eve. But no need to go that way back. The family tree of the great Chinese philosopher Confucius includes more than 80 generations and more than 2 million people, most of them alive. Researchers say that 17 million people are direct descendants of Genghis Khan, the greatest conqueror who ever lived.

Our world inhabits more and more people. We no longer live in villages in which everyone knows everyone else, but in large cities in which we know only few scores of people. We become strangers to each other, we close our eyes and hearts to people in need. We are not family.

But we are. A couple of years ago I prepared a family tree. Many archives from Eastern Europe were lost and my family was somewhat trimmed 70 years ago, and therefore I could climb up the tree only to 1880, in one branch I climbed up to 1830. Overall I have about 1800 people in my tree. Admittedly, many of them are not related by blood but rather through marriage, but nonetheless we are all family.

And then I thought: suppose that one prepares a huge family tree, that includes us all, all the 7 billion souls that roam the earth. We draw a huge graph where each person who ever lived is a node, and each family tie, each marriage and parenthood, is an edge. Every connected component in this graph is one huge family, a group of people who are related by blood and marriage. I guess that we will not end up with one connected component, because of small communities who remained closed for centuries, yet I bet that we will end up with one huge connected component that will include the vast majority of us.

Suppose that you knew that 95% of the people that you see are part of your family. This person who wants to cross the street is the cousin of the cousin of the cousin of aunt Bess. And that driver who drives so slowly is the nephew of the great-grandfather of your neighbor, who is the second niece, twice removed, of the wife of uncle Jim. Will you still honk like crazy?

A family tree may make us all feel like one huge family and help us be better people. On the other hand, it might diminish the significance of the notion of family; if we are all one family, even of those we dislike, then probably one should honk at everyone, family or not. What do you think?