Matching DNA has put me in touch with an extremely large number of Norwegian cousins who share my fifth grandparents from Fatland farm on Halsnøy Island in Hordaland, Norway. What’s more, perhaps due to the large number of them, I am seeing some triangulation of segments among their results.
Halsnøy Island in Hordaland, Norway from the ferry
This started me thinking about the effect of many generations of big family sizes on the number of sixth cousins I might have from a specific set of 5th grandparents. It would seem to me that the larger the number of cousins, the more likely it is that there are some who share good sized segments with me and Dad.
So I did a little simulation in a spreadsheet. It’s very simple, it assumes that the number of children reproducing in every generation is the same so that you can see the differences for different family sizes. I also did a line or two with the real/estimated numbers from the Fatland couple.
If your family consistently had two children who had two children reproducing for six generations you would only have 64 fifth cousins, but if everyone in your family had six children who had six children then you have almost 50,000 fifth cousins. Quite a difference!
The X chromosome has always fascinated me. Whether it is trying to track down the family mild blue/green color blindness or just observing X inheritance patterns in my family and others.
The old farm house at Fatland farm, Halsnøy Island, June 2015
This morning I woke up all excited because I realized that a large piece of my X chromosome comes from my Norwegian 4th grandmother Metta Olsdatter Ve (Fatland) born 1729 on farm Fatland, likely in the house pictured here. She died in 1805 on farm Ve (or Wee) so made it into the 1801 census.
So how did I figure this X inheritance out? My Dad and I share 33.5 cMs of the X chromosome with my fourth cousin once removed Maria and her mother (so it is phased). They descend from a different wife of our common ancestor Aamund Bjørnsen Tvetden. So these 3326 SNPs of X located from 68M to 113M must come from him and therefore from his mother Metta.
No I did not share this insight with my husband when he brought me my morning coffee. I know better than to make his eyes glaze over … only other genetic genealogy aficionados would appreciate this, so I am sharing it here instead.
By the way I am still collecting X statistics, so click here for more on that and please contribute yours
Several of the Ve farms, Etne, Hordaland , June 2015