|Genealogy Tip of the Day|
Have you ever wondered how many ancestors you have? Many new genealogists learn quickly that you start with yourself and that you have two parents, four grandparents, eight great-grandparents, and so on - the number doubling with each generation. The problem with this theory, however, is that by the time you take your family tree back 32 generations you have 8,589,934,592 ancestors - greater than the population of the world today or at any other point in history.
Is it possible that we could have more ancestors than there are people? Of course not! The error in this calculation is that it assumes that all of the ancestors in your family tree are distinct individuals, with no duplication. Yet some names appear on your pedigree more than once. Cousins have married and, if they were first cousins, their children only have six great-grandparents instead of the usual eight since their parents have two grandparents in common. This means they have a 25% decrease in the number of ancestors in the fourth generation back, and this decreased percentage will have an impact on each successive generation going back in time. Multiply that effect by the many marriages between relatives, close or distant, which likely exist in your family tree, and you can begin to see why our ancestors do not multiply to infinity.
It is estimated that as many as 80% of the marriages in history were between cousins (first, second, third, etc.). Until recent times, most of our ancestors lived in small towns and sparsely populated communities where the opportunities for marriage were somewhat limited. Consequently, consanguineous marriages were inevitable. In marriages between distant relatives, they may have even had common ancestors from different generations and not even known they were related.
The consequence of all of this math is that your pedigree, instead of getting wider as you go back (like a triangle) actually widens to a point and then begins to narrow (like a diamond) as the number of distinct ancestors decreases. This important point emphasizes the fact that we are all considerably more inter-related than we might think. You share many of your ancestors with millions of people around the world today - ancestors who were members of nationalities, cultures, ethnic groups, and religions that might surprise you.
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