My Double 3rd cousin versus my brother and my Aunts as shown with my segment mapper

The results came in for my other maternal Aunt so now there are four of us to compare to my double third cousin and still no match on the X! In order to show the comparisons I used my new nifty chromosome segment mapping tool and also added in a bunch of known 5th and 7th cousins to the diagram.


Click on the diagram to go to the full size html page made from the segment mapper. Note that Shipley Munson is my brother.

Since these are all Ashkenazi matches there are likely more matches than in other population groups. More about how we are double third cousins is in my previous post on that topic.

Here is my Aunt S versus me, my brother, and her full sister my aunt T:


Notice how our X chromosomes all match fairly closely. The maximum match on the X is the one Aunt T and Aunt S have (same as I have with my Dad). So as expected, they got at least half identical X inheritance from their parents since their Dad’s X passed to them unrecombined.

 Shipley Munson X 4000000 154000000 177 cM 14410
Aunt S vs. Aunt T
X 1 155000000 182 cM 14565
Aunt S vs. Kitty Cooper X 3000000 150000000 172 cM 13876

Next stop the “Family and Friends” > “Family Traits” page at 23andme where I can see where their genomes are half identical and where they are fully identical:


Looking at this diagram we can see that they in fact share half to full on the entire X chromosome.

So my brother and I got almost all matching X to them from their sister, our mother, as well. Which is interesting since we only match each other for about half our X. However the sections where we don’t match each other are the same sections as our aunts have a full match so I guess we each got a different piece.



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