Question

How many 23 rd great grand parents can1 person have.

Comments

I guess what I mean is this. When I use the relationship finder it says so and so is the 23 rd great grand mother of Trudy Roach. I haven't kept track but I keep finding different names of 23 great grand parent. How many can one person have to fill that exact position in the tree. Thank You all for you answers ;  but I am lost.

---

The 33.5 million number is the correct number for how many 23rd great grand parents one person could theoretically have. In reality it is much smaller since somewhere along the line some distant cousins were bound to get married, an event that undoubtedly happened nunmerous times for every living person today. Still, the number is quite large since the it doubles with every generation and for 25 generations that is 2²⁵ people.

Answer 1

33,554,432

23rd great grandparents + grandparents + parents = 25 generations.

Comments

Fortunately for genealogists, because of marriages between cousins (both close cousins and distant cousins) few of us have nearly that many ancestors at that generation.

---

Somewhere on the internet you can find out when that was and probably will find that the population of the entire world was fewer people than that number.

---

Roughly 750 years ago at 30 years per generation, world population about 400 million, Europe: estimates go as high as 100 million since Europe experienced a population boom from 1000 to 1250.

---

In my family line 20 is the average age for first children, 40 is the average for the last child (excluding cases where the parent dies before that age)

Theoretically a direct line from 23rd GG-Grandparent down the eldest child of each generation (assuming roughly age 20 for the first child) could be as short as 500 years. The line through the last child of each generation would take about 1000.

What I find fascinating (and don't count on my math here, I am tired and hungry) is that if you are someone's 23rd GG-Grandchild, there is potentially another descendant born the same year (if you are the line of eldests and they are the line of youngests) as you who is only the 10th GG-Grandchild of that same ancestor. Conversely if you are the 23rd GG-Child in the line of youngest children, someone born the same year as you could be the 47th GG_Child in the eldest line

Answer 2

The formula for the number of ancestors in a given generation is:

2n = x

where n is the number of generations back 
and x equals the number of individuals in that generation.

See here:

http://dgmweb.net/Ancillary/OnE/NumberAncestors.html

Then google Pedigree Collapse.