Does these GEDmatch results mean I'm related to this person? [closed]

+1 vote
Largest segment = 8.1cM

Total Half-Match segments(HIR)= 389.8cM(10.876Pct)

153874 SNPs used for this comparison

49.587 Pct SNPs are full identical

I'm new to the DNA world and I'm not sure how i should read it. It was a one to one comparison. My boyfriend's mom change it to SNP window to 25 and segment size to 3.0
in Genealogy Help by Sarah Nyagami G2G Crew (400 points)
closed by Darlene Athey-Hill

3 Answers

+4 votes
Best answer
I think you must have changed the default for "SNP window size threshold." and "Minimum segment cM size" to get such a large total for such a small largest segment size.

To test this, I changed the defaults for these and compared myself to my lowest match and got the following:

Largest segment = 9.0 cM
Total Half-Match segments (HIR) = 561.4 cM (15.659 Pct)
133 shared segments found for this comparison.
145586 SNPs used for this comparison.
52.264 Pct SNPs are full identical

This shows how important it is not to change the default settings.
by Samantha Thomson G2G6 Pilot (176k points)
selected by Darlene Athey-Hill
+2 votes
Looks to be 2nd-3rd cousin to me.
by Rob Judd G2G6 Mach 9 (99.4k points)
+2 votes

That is extremely strange. You are certain the largest segment is 8.1cM? But almost half of your genomes are fully identical? 

Fully identical regions appear only between full siblings or double-cousins, which is a rare relationship category. You don’t share enough total cM to be full siblings, but even full siblings would only be fully identical on about 25% of the genome — no way it would be 49.6% And in the other hand if you share 390cM with someone you are almost certain to have a matching segment longer than 8.1cM.

This almost looks invented. I can’t understand what would produce these numbers. A glitch?

by Barry Smith G2G6 Pilot (240k points)
Yeah my boyfriend's mom change the ratio. She wanted to see if we were related she change the SNP to 25 and the segment cM to 3.0

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