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I'm matching with an interesting connection present in MyHeritage and Gedmatch. My Raw data are from 23andme.
On Gedmatch, here is all the connection before triangulation that I have with a woman (One to one autosomal with the option "Prevent Hard Breaks") :
One to one autosomal (7CM Threshold) :
Chr---------B37 Start Pos'n---------B37 End Pos'n--------CM----------SNPs
1--------------34 071 525---------------40 184 733---------9,2----------359
=> SNP's in MyHeritage : 2944
Chr----------B37 Start Pos'n----------B37 End Pos'n----------CM)----------SNPs
6-1------------41 366 580 --------------44 568 740-------------7,1 ----------227
6-2------------166 684 657---------------170 335 567----------8,9-----------269
=> SNP's in MyHeritage : 2176 (chromosome 6-1) and 2688 (chromosome 6-2)
=> Total value (with 7CM Threshold) : 25.2CM
=> Total value (with 3CM Threshold) : 38.7CM ( plus 2 segments on chromosome 6 (3.7CM, 6.7CM), plus 1 segment on chromosome 5 (3.1CM) )
In the Q matching One to one :
chromosome 1 : Q=34
chromosome 6-1 : Q=17
chromosome 6-2 : Q=34
The triangulation (7CM Threshold) in Gedmatch gives this, in B37 (I also give B36 and B38) :
1 Segment of chromosome 6-1: 6 correspondences (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6) B36: 6 correspondences ranging from 6.6CM to 6.9CM. (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6) B38 : 6 correspondences ranging from 6.6CM to 6.9CM (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6)
=> All below 7CM. That's really borderline for the 6.9! Should we take this into account?
1 Segment of chromosome 6-2 : 2 correspondences => 8.7CM (for the 1st match which is really interesting) and 6.7CM (for the 2nd). B36 : 2 correspondences. Same as B37. B38 : 2 correspondences. Same as B37.
=> So 3 segments including 2 on the same chromosome 6.
An interesting fact: I match on 1 segment with a male on 8.8CM after triangulation. For this case, I also match on this 6-2 chromosome, but on a segment right next to the segment I share with this woman. And I know, by classical genealogy, that this woman and this man are distant cousins (sure and certain). But they do not share any genetic segments with each other on Gedmatch. I wanted to point this out.
So my question is : Is there any relationship or not (Close or distant by centuries, whatever. I just want to know if there is a true connection or not.)?
And if relationship, I have to go back to how many centuries-generations to facilitate my research in classical genealogy?
Thanks for the reply
PS : I discovered on Gedmatch that I was matching with other people (3 especially) who I know are cousins with this woman I am related to (I recognize them by their typical surname and recognized as cousins in classical genealogy). I share with these 3 persons only 1 segment of 10.5CM for the first one, 8.8CM for the second one and 7.4CM for the third one (after triangulation), so common ancestors which make me think that there is a relationship, maybe. On Gedmatch, there is no segment in common between these 3 persons and the woman.
The word you used which sums it up best is "maybe." If you are matching (using the default values in GEDmatch) to a set of cousins whose relationship to one another is known, then it's more promising that there is a connection. But if you are playing around with the defaults in order to "find" matching segments then it may not be a true connection. Do not change the 7 cM threshold.
I have modulated the threshold just as an indication (3CM).
I use 7CM Threshold as a basis for this study. All the CM found are in 7CM basis.
And I know that the other matchs are cousins of this woman, but they don't share any segment. But I share segments with all of them.
If you are matching (using the default values in GEDmatch) to a set of cousins whose relationship to one another is known, then it's more promising that there is a connection.
If I match with 2 distants cousins of this woman, but these cousins don't have any segments in common with this woman, and these 2 cousins have 1 segment in common, is there a relationship with me and this woman? That is the question for me. If someone have the answer, you are welcome.
As I said it's possible these segments indicate a genealogical relationship to a common ancestor, but it is not conclusive until you can triangulate segments.
For example, a few years ago I noticed I was related to several people tested who shared a common ancestor with one another. Some of them did not match all the others, but they all matched at least some of the others. They were all about 3rd or 4th cousins to one another and part of a coordinated family DNA project. For me the matches were on several different segments but there were a couple of triangulations (two or more who matched me on the same segment). Their MRCA (most recent common ancestor) I later discovered also turned out to be one of mine (I was adopted and had no family tree to start out with).
What is the reason you want to prove a relationship to the woman in question? Does the MRCA these people share have any known connection to your genealogy? Does it involve an endogamous population?
As I said it's possible these segments indicate a genealogical relationship to a common ancestor, but it is not conclusive until you can triangulate segments.
I have done a triangulation. See my 1st post above. What do you think about please?
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For example, a few years ago I noticed I was related to several people tested who shared a common ancestor with one another. Some of them did not match all the others, but they all matched at least some of the others. They were all about 3rd or 4th cousins to one another and part of a coordinated family DNA project. For me the matches were on several different segments but there were a couple of triangulations (two or more who matched me on the same segment). Their MRCA (most recent common ancestor) I later discovered also turned out to be one of mine (I was adopted and had no family tree to start out with).
Thanks for this example! I triangulate with this match in the same way (see 1st post). I have several matches for each segment in triangulation. This is good news, I'm really happy for you!
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What is the reason you want to prove a relationship to the woman in question? Does the MRCA these people share have any known connection to your genealogy? Does it involve an endogamous population?
I belong to a noble lineage from the Maghreb (and in Andalusia. I have also several matches from spain people), but I do not know the name of this lineage (I don't understand how my family got away from its lineage). This woman belongs to a known lineage in my country. The other matches also belong to this common lineage, but with another name because the great lineage was branched into several sub-lineages. So I thought that the number of segments I have in common the most will be the name of my lineage. As I share 3 segments with this woman, but only one segment with the other men (8.8CM for the 1st, 10.5CM the 2nd, 7.3CM for the 3rd after triangulation), I thought that I belong more to the woman's lineage than to the others, who are all distant cousins.
For endogamy, it is possible, but I can't say if these segments are related to this endogamy.
I thought you said none of these people match you on the same segment as any of the others. You mentioned triangulation with a person who had a segment adjacent to a segment from another match, which is not a triangulation. By triangulation, I mean you have to share the same segment with two or more people. They have to match each other on the same segment where they match you. This way (assuming the segment is large enough, say over 9 cM) it indicates you all share a common ancestor, but you have to do more work to determine which ancestor you share.
A noble lineage sounds like it could be very old, which would be difficult to prove through autosomal DNA. Autosomal DNA is good for confirming relationships up to 5th or 6th cousins. After that, you may not even have inherited any DNA from the lineage. You may share DNA with these people from a different line. Is there a Y-DNA Project for the lineage these matches share?
I thought you said none of these people match you on the same segment as any of the others. You mentioned triangulation with a person who had a segment adjacent to a segment from another match, which is not a triangulation. By triangulation, I mean you have to share the same segment with two or more people. They have to match each other on the same segment where they match you. This way (assuming the segment is large enough, say over 9 cM) it indicates you all share a common ancestor, but you have to do more work to determine which ancestor you share.
You didn't understand my 1st message. maybe my explanation was not good.
The triangulation study I did is exclusively on my link with this woman, here is again :
The triangulation in Gedmatch with this woman (Gedmatch default settings) gives this, in B37 (I also give B36 and B38) :
1 Segment of chromosome 6-1: 6 correspondences (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6)
B36: 6 correspondences ranging from 6.6CM to 6.9CM. (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6)
B38 : 6 correspondences ranging from 6.6CM to 6.9CM (6.9CM, 6.9, 6.9, 6.7, 6.6, 6.6)
=> All below 7CM. That's really borderline for the 6.9! Should we take this into account?
1 Segment of chromosome 6-2 : 2 correspondences => 8.7CM (for the 1st match which is really interesting) and 6.7CM (for the 2nd).
B36 : 2 correspondences. Same as B37.
B38 : 2 correspondences. Same as B37.
=> So 3 segments including 2 on the same chromosome 6.
After that, I said that i have an another triangulation with another people who are cousins with this woman. And one of them triangulate in the same chormosome 6 but with a segment near the segment that I have in common with the woman. You understand (see the part "an interesting fact" in my 1st post)? It is to show you that this chromosome 6 is very special, because I have relations in this one with 2 people in Gedmatch and another in MyHeritage. And I know that they are cousins eatch other.
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A noble lineage sounds like it could be very old, which would be difficult to prove through autosomal DNA. Autosomal DNA is good for confirming relationships up to 5th or 6th cousins. After that, you may not even have inherited any DNA from the lineage. You may share DNA with these people from a different line. Is there a Y-DNA Project for the lineage these matches share?
With this triangulation with this woman, what do you think about the degree of cousinship that I can have with this woman?
Yes, there are projects on FtDna, I am waiting for my raw data to be validated by the site.
I don't have Tier1 tools on GEDmatch so I don't know what their triangulation tool is doing. So you're right, I don't understand what you posted.
The traditional triangulation method is to find a segment that matches three people (yourself and two others). Let's say you are A, and you have match B and match C. They match you on the same location on chromosome 1. Then you have to run a comparison between B and C to see if they match each other in the same location. Is this happening with your matches who share a known ancestor?
Some segments you listed are small (around 7 cM and below) and may not be significant.
The degree of cousinship is hard to predict with such small segments. She may be related to you in multiple ways, all distantly. If you can test a parent, it would help you narrow it down.
I use the triangulation of tiers-1. The principle is the same.
I noticed one thing. When I triangulated in MyHeritage, I only found matches with chromosome 6-1 (this woman is present in MyHeritage and Gedmatch).
On Gedmatch, I was able to triangulate on 3 segments. Yes, these segments are small. But I figured that with newcomers on Gedmatch I could find triangulations up to 9.2CM for chromosome 1, 7.1CM for chromosome 6-1 and 8.9CM for chromosome 6-2 (because basically they are that long). So triangulate on the whole segment.
For the moment this is not the case.
But I learned another very important thing to do on Gedmatch that admins said on Gedmatch forum : "The only segment lengths that we use on GEDmatch are those that are produced by the One-to-One Comparison tool using the default parameters plus the "Prevent Hard Breaks" option. The One-to-One tool actually compares individual SNP scores. Many of the other tools do not; instead, they make use of GEDmatch "batch processing" results, which are based on a smaller set of SNP's in a way that greatly speeds processing when it is necessary to compare one kit against all others (as is the case for Triangulation, One-to-Many, etc.) The One-to-One tool is the gold standard for GEDmatch."
I personally agree with this point of view, as the explanation is really interesting. My question is now, is there any cousinship with these segments that I have in common and that are higher than 7CM using this method :
9.2CM for chromosome 1,
7.1CM for chromosome 6-1
and 8.9CM for chromosome 6-2 ?
Normally, we could say 'yes'. But I've read so much that my mind is muddled and I don't know what to think anymore. Because I have noticed that people do not agree with each other about "segmentation" science. I would like to have your personal opinion on this case please (with segments 9.2, 7.1, 8.9CM=25.2CM).
thanks
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