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  #1  
Old 2nd July 2017, 11:41 AM
TwiddlingThumbs TwiddlingThumbs is offline
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Join Date: Jan 2016
Posts: 132
Grouping kits in Y-DNA results chart

As a surname project administrator, I think grouping the kits in the Y-DNA results chart in a useful manner may be one of the more important tasks. Grouping by haplotype does not seem sufficient because in most cases the haplotype group will be so broad that it includes groups of people who are not descended from a common male ancestor within the genealogical time frame.

Ideally, I think the kits should be put into groups of testers whose STR results show are all probably descended from a common male ancestor within the genealogical time frame, based on FTDNA genetic distance guidelines. See:
https://www.familytreedna.com/learn/...s-interpreted/
https://www.familytreedna.com/learn/...s-interpreted/
https://www.familytreedna.com/learn/...s-interpreted/
https://www.familytreedna.com/learn/...s-interpreted/
https://www.familytreedna.com/learn/...s-interpreted/

I have written a software program that does just that. If you are interested in seeing what the results of such an analysis look like for your surname project, I would be happy to run your project data through my program. Please send me a message if you are interested.

For an example of a surname project that used the program to group the kits, see the Ashley project chart at: https://www.familytreedna.com/public...frame=yresults
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Old 2nd July 2017, 12:16 PM
georgian1950 georgian1950 is offline
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Like it!

While I am not a project administrator or even a Y-DNA expert, to me most project results are not very well organized. Looks like you have made a big effort to change that.

Jack Wyatt
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  #3  
Old 4th July 2017, 08:50 PM
Martin Potter Martin Potter is offline
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Grouping by haplogroup is good and useful, provided that you get your members to test for their terminal SNP. As the discovery of new SNPs progresses, this successive testing can become a never ending process, but it is by such a goal that major discoveries are made.

I group all my members by haplogroup, as far as that can be determined.

... Martin
(Foad, Huntsman, and Mugford projects)
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Old 4th July 2017, 09:27 PM
TwiddlingThumbs TwiddlingThumbs is offline
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"Grouping by haplogroup is good and useful, provided that you get your members to test for their terminal SNP"

That's a big proviso. Maybe someday we will get there, but we are not there yet. Currently, if you group only by haplotype, you end up with big groups that contain lots of families that you KNOW, based on STR results, are not related within the genealogical time frame. You need to group by STRs to separate them out. A good hybrid approach is to group by STR results but indicate in the group name which haplotype the members of the group belong to. If the STR results indicate that the members of the group are related, it is safe to say that they share the same haplotype even if they haven't all tested yet.

Last edited by TwiddlingThumbs; 4th July 2017 at 09:41 PM.
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  #5  
Old 6th July 2017, 02:25 AM
Martin Potter Martin Potter is offline
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Quote:
Originally Posted by TwiddlingThumbs View Post
If the STR results indicate that the members of the group are related, it is safe to say that they share the same haplotype even if they haven't all tested yet.
It has been demonstrated a number of times that men can match quite closely in STR values and yet have different haplotypes. This happens due to 'convergence' by random mutation of STR values from quite different populations.

The true test of relatedness is sharing of SNPs along a branch of the haplotree right down to the terminal one. It is not enough to be R1b-M343+, as predicted by the lab. You have to test successively :
R1b-M343+ → L11+ → P312+ → L21+ → DF13+ → L513+ → S6365+ → BY17+ etc, down to the most recently discovered SNPs in that sub-branch. If the TMRCA of the terminal SNP is less than a few hundred years (most of them have not been discovered yet, but will be eventually), then you are reasonably assured of a common, shared paternal-line ancestor.

STR matches can never be more than approximate.
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Old 8th July 2017, 01:33 PM
TwiddlingThumbs TwiddlingThumbs is offline
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I agree that SNPs are more definitive, but in most surname projects, only a very small minority of members have taken a SNP test. The haplotype assigned to the vast majority of kits in most surname studies is just a "predicted" haplotype, which (i) is based solely on their STR results and (ii) too general to separate all the kits into separate related families. (I note that your Foad, Huntsman and Mugford projects are very unusual in that virtually every member has had SNP testing. Most surname studies are a sea of red "predicted haplotypes".)

Since every kit on the YDNA results page has STR results, while, in most cases, only a small minority have SNP results, basing groups on STR results is the only option for most surname projects.

Also, while I agree that unrelated men can have matching or close STR results, particularly on the lower STR tests (eg, 37 or lower), the chances of men with the same surname (as assumed by the FTDNA genetic distance guidelines) having close STR results and yet being unrelated, is fairly small. Therefore, in the context of a surname project, using STRs to group kits is very reasonable and sound, provided you don't include in the groups any kits with different surnames (unless there is reason to believe that they are biologically descended from someone with that surname).
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