How many Ancestors do you really have - Mind Blowing

[rp76226]

Each generation of direct ancestors (parents and grandparents) doubles in the number of grandparents you have as each ancestor has a mother and a father that created them. Using 30 years old as the average age of parents when each of your direct ancestors was born thus defines a new generation as a time span of 30 years. Here's the math:

10 Generations = 300 years = 1,024 grandparent ancestors for just that single 10th generation.

20 Generations = 600 years = 1,048,576 grandparent ancestors for just that single 20th generation.

30 Generations = 900 years = 1,073,741, 841 grandparent ancestors for just that single 30th generation. In other words over one billion ancestors just for you just for that generation.

40 generations – 1,200 years = 1,099,511,645,184 grandparent ancestors for just that single 40th generation. In other words over one trillion ancestors just for you just for that 40th generation.

Never has there been anywhere close to one trillion people from the beginning of time (most estimates range from 60 to 100 billion people that have ever lived on earth, covering millions of years). Yes, lots of these ancestors were also ancestors for many other descendants. Still, the math boggles the mind (at least my mind)!

Ron

[MarcuccioV]

It's amazing. On my dad's side I found that my 12GGf is the same person as my wife's 12GGf (her direct paternal line, indirect on mine).

I've had a couple Geni connections for my Italian (maternal) side that tied in through multi-generational links to an Italian spouse on my wife's (non-Italian) side.

Yup. Pretty mind-blowing...

[greglam]

This is fascinating. Thank you so much for providing these numbers.

I am working on my family tree on Ancestry and tried to manually calculate it out once to the level of my 5th Great-Grandparents. I think I got to the 4th GG and was like, "Wait a minute..."

Here is a page that calculates by generation back to the 17th great-grandparents how many ancestors you have, and then how many descendants - theoretically - one set of 17th great-grandparents could have.

http://freepages.rootsweb.com/~pamonval ... owbig.html

On AncestryDNA, I have 8,704 matches, only 392 of whom are 4th cousins (shared 3rd great-grandparent) or closer. And the 8,704 are only of the people who have taken the AncestryDNA test, imagine how many I *REALLY* have! It's mind-boggling!

[joetucciarone]

Here is an interesting discussion about this topic. The author basically says that, once we go back far enough, the number of unique ancestors we really have is less than the math seems to indicate:

https://news.legacyfamilytree.com/legac ... -have.html

[greglam]

Here is an interesting discussion about this topic. The author basically says that, once we go back far enough, the number of unique ancestors we really have is less than the math seems to indicate:

https://news.legacyfamilytree.com/legac ... -have.html

Thank you very much for sharing this article, Joe! I'm going to share it with a couple of my relatives (4th cousins and closer) who are all on the "family tree journey" with me.

A couple of thoughts:

1)If I recall correctly, I read some time ago, maybe 10+ years ago now, that everyone alive today is descended from the same 48 couples or individuals, I can't remember which. Anyway, less than 100 people. And, further, I seem to recall reading about a "Genetic Eve" being identified, too, from which ALL modern human beings, i.e. rational, upright walking, homo sapiens descended. I could be wrong, though.

2)I found that article linked above (as well as some of the comments) interesting, in that my mother is a Riley, one of the most common surnames in Ireland. My 14th great-grandfather was Cathal Dommhnall Ban O'Riley, King of East Breifney, Beyond the Pale, Ireland. Cool, right? But, nothing special, as all those with the surname Riley/O'Reilly/etc are similarly descended. And even at certain points we find Rileys and O'Reillys marrying, thus truncating the possible number of unique ancestors 10-15 generations back. And while I have no love of "royalty", it is still kind of cool to see the lines and titles of some of my very distant ancestors, some of whom were also Scottish and English nobles.

3)On a personal note, the diamond shape of my particular family tree may begin at a more distant level than discussed in the article as my mom is Irish and Hungarian, and my dad is Italian and Sicilian. And while I've gotten back to my 15th or 16th GGF on one branch of my mom's side, as deep as I've been able to get on my dad's side is my grandfather's 3rd GGF in Abruzzo.

Anyway, super relevant and interesting topic, thank you all!

-Greg

[joetucciarone]

You're welcome, Greg. This is a fascinating topic; for most of us, the math gives us the number of our unique ancestors to the 5th or 6th generation. Somewhere further back, our distant ancestors who were cousins were marrying, so the number of unique ancestors each of us have is less than the math indicates.

Also, you mentioned "Genetic Eve;" here's a Wikipedia article about Mitochondrial Eve, from whom everyone alive to day presumably descends:

https://en.wikipedia.org/wiki/Mitochondrial_Eve

[MarcuccioV]

I also have much shorter branches on my Italian side than my non-Italian side. Unfortunately that's due to lack of official documentation, and I'm sure it's not limited to just Italy...

[MarcuccioV]

Another consideration I have found (especially in smaller communes and hamlets) is that family surnames keep repeating (even between married couples) which would mean multiple MRCA's further distant which would lessen the number somewhat. In my family's case I have a pair of 4GG's that are on 2 separate lines (both from my grandfather); one on his paternal side & one on his maternal.

I'm sure that is not that uncommon an occurrence.

[PippoM]

Another consideration I have found (especially in smaller communes and hamlets) is that family surnames keep repeating (even between married couples) which would mean multiple MRCA's further distant which would lessen the number somewhat. In my family's case I have a pair of 4GG's that are on 2 separate lines (both from my grandfather); one on his paternal side & one on his maternal.

I'm sure that is not that uncommon an occurrence.

My wife is from a village (2000 people) in the province of Viterbo.
I have her tree back to the 1600's. Well, there's more than one ancestor who appears four times in it. One, in particular, had four children who are ALL her ancestors through different branches.

[MarcuccioV]

My wife is from a village (2000 people) in the province of Viterbo.
I have her tree back to the 1600's. Well, there's more than one ancestor who appears four times in it. One, in particular, had four children who are ALL her ancestors through different branches.

I rest my case...