Dick Eastman recently wrote an article on how many ancestors can you have and he covered 20 generations.
I was glad to see that most people realize that many people not on earth at that time so we are repeat of ancestors in our lines.
I for one have several in the last 7 to 10 generations. When a brother and a sister have children that marry they share the common parentage. When the daughter of one line marries the son of the Uncles line again you are repeating kinship. It is fun to watch how this reverts backwards.
George Schweitzer did a great talk on this many years ago for the San Diego Genealogical Society. Before computers were so prolific and people could so easily see the compiled over use of same family in different lines.
Recently holding a meeting at Fillippi's in Chula Vista I had to point out to fellow members the great chart they have on their entry way wall on the family lineage. A Gold Star to them to showing it up front and so beautifully done. My husband saw it three weeks ago when we ate there with a Family Reunion, and brought it to our family's attention. He was impressed with the size and design and information presented.
On my mothers side of the family we have to sets of duplications in the STOUT and DuVALL lines.
On my fathers side we have duel duplication in the FOULK and MYER's lines. We probably have others since I have found FULLER on both sides more than once but still at a stumbling block for some results.
Between the two lines (Mom and Dad) we have 5 direct JONES lines, 2 of those lines may interlink.
On Mom's side we go back farther before the doubling on one but on Dad's it is rather close for both.
We can go back five generations and see the duplication. The DuVall is close for MOM five Generations. The Stout is probably 10 generations back from myself.
What I do find is a lot of cousins marry cousins then making them double cousins but not blood related which can make it very interesting when trying to explain to someone whom is who.
My Grandfather and his sister Grace married in to the Scott line, he married Inez and Grace mar Great
In doing research on line in the old AOL Forum I made connections to one person 13 times the same lines we shared. That seems like we should carry a lot of the same traits and genes. But I have never asked the DNA people if they have worked that angle before. (13 parent sets)
How many times have you connected with another person on line? I have a few at 4 and 6 and most at only one lineage (2 names) .