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Old 26th October 2016, 06:57 PM
dietcokelemon dietcokelemon is offline
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Very large largest segment

My father-in-law's matches has what appears to be an unusual result. 200 total CM but with 60 as the largest segment. I've never seen a segment that large that wasn't immediate family, but, with 200 total CM, this isn't that.

I've looked through all the expected CM charts, but they focus on total CM. I've heard people say that the largest block is primarily about confidence level, but... that doesn't seem like it would explain this.

For reference, two of my grandparents' first cousins are ~300/~40.

In another kit I manage, there is a similarly odd result: a 103/49 marked as 4th cousin-remote, and 134/45 marked as 2nd to 3rd cousin. It seems weird that the 49 largest-block would be so low, and that a similar largest-block with only 31 extra CM would be predicted to be so much closer.

(all of these results are for Ashkenazi Jews)

Any thoughts would be appreciated. Thanks!
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Old 27th October 2016, 09:51 AM
mattn mattn is offline
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Quote:
Originally Posted by dietcokelemon View Post
My father-in-law's matches has what appears to be an unusual result. 200 total CM but with 60 as the largest segment. I've never seen a segment that large that wasn't immediate family, but, with 200 total CM, this isn't that.

I've looked through all the expected CM charts, but they focus on total CM. I've heard people say that the largest block is primarily about confidence level, but... that doesn't seem like it would explain this.

For reference, two of my grandparents' first cousins are ~300/~40.

In another kit I manage, there is a similarly odd result: a 103/49 marked as 4th cousin-remote, and 134/45 marked as 2nd to 3rd cousin. It seems weird that the 49 largest-block would be so low, and that a similar largest-block with only 31 extra CM would be predicted to be so much closer.

(all of these results are for Ashkenazi Jews)

Any thoughts would be appreciated. Thanks!
The larger segment could be an indication of a closer relationship such as a 3rd to 4th cousin. They are probably related multiple times being Ashkenazi Jews with the smaller segments coming from the distant relationships and the larger segment coming from a closer relationship. You can look at the Shared cM Project, they do have some charts for the longest reported segment for various relationships along with whether there is endogamy or not in that person's pedigree.

http://thegeneticgenealogist.com/201...hared-segment/
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Old 27th October 2016, 11:42 AM
dietcokelemon dietcokelemon is offline
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Thanks! I somehow had missed that link and it is extremely helpful.
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Old 27th October 2016, 12:11 PM
Serket Serket is offline
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I have a match that is 78 cm in total with a longest block of 51 cm. We are confirmed as 2nd cousins, three times removed and I think he's actually deceased now.
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