In order to be born, you needed:

       2 parents

       4 grandparents

       8 great-grandparents

     16 second 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

                                   .  .  .

Think for a moment:

ü How many struggles?

ü How many battles?

ü How many difficulties?

ü How much sadness?

ü How much happiness?

ü How many love stories?

ü How many expressions of hope for the future did your ancestors have to undergo for you to exist in this present moment...

In theory, the number of ancestors you have double each generation backward. When you reach 25 or 30 generations into the past, 600-700 years ago, the number of ancestors you should theoretically expect is larger than the entire human population of that time. That is obviously impossible and begins to show how challenging it can be to track ancestry. There’s something wrong with the math.

The answer is that, as you go back in your family tree, ancestors will start to pop up more than once. If you go back two generations to your grandparents, you have four different ancestors. If you go back two more, you almost certainly have sixteen distinct ancestors. However, if you go back eight generations or about 200 years, the math would predict that you have 256 ancestors, but you almost certainly don’t. In fact, you may have closer to 200. This is because the farther back you go, the more "repeat" ancestors you will find. In fact, after 12-15 generations, the total number of your ancestors barely increases each additional generation that you go back.

This is a phenomenon known as “pedigree collapse,” in which distant relatives mate with each other creating a family tree in which an ancestor will appear in multiple places. In the royal families of Europe, the pedigrees collapse in the very recent past. For example, both Queen Elizabeth II and her consort, Prince Philip Mountbatten, are the great-grandchildren of Queen Victoria

This family tree shows how both Queen Elizabeth II and her husband, Prince Philip Mountbatten, are the great-grandchildren of Queen Victoria.

The sum of all this is that we are all related and probably a lot more closely than you think. In fact, scientists estimate that the most recent common ancestor of all humans lived just 2,000-3,000 years ago somewhere in the Levant or Northern Africa. This is different from Y-chromosome Adam or mitochondrial Eve, who gave rise to very specific lineages that then came to comprise the entire population.

Bible stories aside, it is exceedingly unlikely that Y-chromosome Adam and mitochondrial Eve lived at the same time, let alone in the same place, and they were certainly not alone in the world. However, they were real living people that made their way in the African savannah of a bygone era, totally unaware of their impending genetic legacy.