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peloponnesian
02-14-2021, 05:58 PM
So I was browsing my 23andMe DNA matches and there's an American guy with whom I share a 37.59cM chunk on chromosome 16 (0,51% of our DNA).

https://i.imgur.com/iFqsYwh.png

I browse his results and sure enough, he scores 11,6% "Greek and Balkan" (Greek great-grandfather). Then I'm like "wait, that name seems familiar" and I go to MyHeritage, with which both me and my father have tested. I try to search for his name, no results. Then I switch to my father's profile and there he is, in the first page of his DNA matches. They share 51.6cM, including the same chunk I share with him on 23andMe (actually he shares a bit more on this region with my father).

https://i.imgur.com/Ly1BqKa.png

Curiously, MyHeritage doesn't give him any "Greek and South Italian" or "Balkan" in his ethnicity estimate, he is 97.4% "North and West European" and the rest "East European" (both of which my father doesn't score at all). But he has a family tree and a list of surnames on MyHeritage and one of them is Greek, which is in line with his 23andMe results.

I also checked Gedmatch but he doesn't seem to have an account there.

What could explain this weird disparity? Why is there such a large difference in the SNPs tested for the same chromosome region (4511 on 23andMe VS 13184 on MyHeritage)? I don't care much about finding distant relatives on my genealogical tree but this could be of interest to those who dig into this stuff.

JerryS.
02-15-2021, 10:39 AM
interesting. I await to hear what others think is the reason for the miscalculation and missed matching.

peloponnesian
02-15-2021, 11:06 AM
I found that it's free to upload my 23andMe to MyHeritage so I did that and I'm waiting to see if their algorithm finds the match with the different raw data :)

This post wasn't meant as a dig on MyHeritage btw, I think they're a promising company especially for Europeans.

lana6765
02-15-2021, 12:23 PM
So I was browsing my 23andMe DNA matches and there's an American guy with whom I share a 37.59cM chunk on chromosome 16 (0,51% of our DNA).

https://i.imgur.com/iFqsYwh.png

I browse his results and sure enough, he scores 11,6% "Greek and Balkan" (Greek great-grandfather). Then I'm like "wait, that name seems familiar" and I go to MyHeritage, with which both me and my father have tested. I try to search for his name, no results. Then I switch to my father's profile and there he is, in the first page of his DNA matches. They share 51.6cM, including the same chunk I share with him on 23andMe (actually he shares a bit more on this region with my father).

https://i.imgur.com/Ly1BqKa.png

Curiously, MyHeritage doesn't give him any "Greek and South Italian" or "Balkan" in his ethnicity estimate, he is 97.4% "North and West European" and the rest "East European" (both of which my father doesn't score at all). But he has a family tree and a list of surnames on MyHeritage and one of them is Greek, which is in line with his 23andMe results.

I also checked Gedmatch but he doesn't seem to have an account there.

What could explain this weird disparity? Why is there such a large difference in the SNPs tested for the same chromosome region (4511 on 23andMe VS 13184 on MyHeritage)? I don't care much about finding distant relatives on my genealogical tree but this could be of interest to those who dig into this stuff.

Was it an upload or did you test with MyHeritage?

I uploaded both 23andme and Ancestry data and got different matches. Some of them were the same and some of them were closer with one kit than the other.

peloponnesian
02-15-2021, 01:32 PM
Was it an upload or did you test with MyHeritage?

I uploaded both 23andme and Ancestry data and got different matches. Some of them were the same and some of them were closer with one kit than the other.

It was a MyHeritage test. I've tested with both 23 and MH, my father only MH.

My initial post wasn't very clear, sorry. On 23andMe I match on this segment with the other guy, but on MyHeritage only my father matches with him, but it's on the same segment. So I assume MyHeritage messed up with their genotyping/imputation/matching algorithm - or there's a different explanation that I have not thought of :P

JerryS.
02-15-2021, 08:14 PM
I found that it's free to upload my 23andMe to MyHeritage so I did that and I'm waiting to see if their algorithm finds the match with the different raw data :)

This post wasn't meant as a dig on MyHeritage btw, I think they're a promising company especially for Europeans.

the raw data transfer from another company vs. an actual spit sample that they decode on their own could be different in their estimation of things. however, the matches should still be the same.

peloponnesian
02-16-2021, 07:19 PM
the raw data transfer from another company vs. an actual spit sample that they decode on their own could be different in their estimation of things. however, the matches should still be the same.

Yeah, it's possible he didn't actually test with MyHeritage and just transferred from 23 so the imputed data may have some wrong calls (?). But then how he does match with my father on MH? :confused: