Genealogical Paradox?

Question:

Genealogical Paradox?

So... the world's population has been increasing since humanity began... but I have 2 parents, 4 grand-parents, 8 gg-parents, 16 ggg-parents, 32 gggg-parents, 64 ggggg-parents, 128 gggggg-parents, 256 ggggggg-parents, 512 gggggggg-parents, 1024 ggggggggg-parents... so at what point do my 'increasing number of ancestors' meet the 'increasing population' coming the other way? And THEN what happens?

Best Answer - Chosen by Asker: Not a paradox at all. You are assuming that all individuals are "unique" in their relationship to you. That is not at all true.

Robert the Bruce of Scotland is my 20th great-grandfather. He is also my 19th and 22nd great-grandfather. Different wives or consorts and later intermarriage between descendants account for this.

I have also discovered that my mother and father have a common ancestor, thus they are "cousins".

Often you have family intermarriage. A descendant of your nth great-uncle, marries a descendent of your nth great-grandfather. At some point, your maternal and paternal lines will intersect, thus you would have the same person as a grandparent multiple times. Now factor in that it wasn't so long ago that people had multiple spouses and many children with each, the occurrence of intermarriage, especially many generations afterwards, is actually quite common. In fact, in royal/noble families, you don't often have to go many generations before such intermarriage happens.

So while you do have 1024 gggggg-parents as far as "positions" on a family tree, it is more likely than not that many of those 1024 are the same person. Don't forget you're not the only offspring of all those people. Each of your 4x Great Grandparents could have hundreds or even thousands of living descendants today. Imagine an island with 100 people, 50 men, 50 women. They marry and have 2 kids each. The kids all marry at age 20, the adults all die at age 40. They keep on doing this for 12 generations. The population will never get to be over 200. By generation 12 everyone will look alike and be related to each other 4,000 ways from Sunday, but the population won't get bigger. You are assuming that your direct blood line (ie Parents, Grand Parents etc) doubles every generation, you are failing to take into account that Cousins marry and this cut down the number of direct blood ancestors you have. eventually, it winds down again. I'm related to some of my ancestors in different ways. My parents are distant cousins, and they didn't think they were related at all. I live in SE Pennsylvania, and my family has lived in the same county since it's inception in 1752. Many of the families intermarried, so they all tie in together multiple times.