DNA Segment Triangulation
By Kitty Cooper
Blogger

blog. kittycooper. com
What is a DNA segment?





Ancestry DNA can be uploaded to any or all of these sites to see segment matches in a chromosome browser:
- GEDmatch.com
- MyHeritage.com
- FamilyTreeDNA.com $


5 cousins compared, but do they match each other


Data from the ISOGG wiki at https://isogg.org/wiki/Identical_by_descent

ISOGG wiki entry for Triangulation
https://isogg.org/wiki/Triangulation
Triangulation
- When three people all match each other at the same autosomal DNA location we call it Triangulation.
- From ISOGG: "If you have at least three people with a common ancestor matching on the same segment then you can infer that the segment came from that ancestor. "
- Inversely, if three people all match each other on the same good sized segment then you can infer they have a common ancestor.(larger than 7cM but 11cM or bigger is preferred)

Blaine Bettinger's DNA relatedness chart, from his site http://www.thegeneticgenealogist.com/
August 2017 chart is at
https://thegeneticgenealogist.com/wp-content/uploads/2017/08/Relationship_Chart_FINAL_August_2017.jpg


George
Anna
Anton
Anna
Henry
(me)
GGG
GG
G
GGG
GG
G



KRISTINE v my cousins

Kristine compared to Mike and John on chromosome 11
John
versus
Mike
Chr 11


Kristine compared to John, George and Henry
John versus 2nd cousins
George (PG) and Henry
Chr 14


(George)

Kristine compared to Mike and Katy
Mike versus Katy
Chr 16




GGG
GG
G


The total number of cMs seemed low until I realized that she was from a different wife of Charley so a HALF 1C2R

Only one of the five segments MM shares with Kristine is in the same location as the other cousins, the one on chr 11, does it triangulate?
Kristine compared to Mike and John on chromosome 11
John vs Mike
Chr 11



WOLD homestead 2015 in Vestfold, Norway
Questions?

Make a Master Spreadsheet of your segment matches
Template available in my downloads area http://blog.kittycooper.com/?ddownload=2556
GenomeMate is another way to organize this data as is DNApainter.com

Every company but ancestry will give you the segment information in this format or similar - you can cut and paste into your spreadsheet
Add the columns you need, Match name, GEDmatch number,MRCA ...




My fourth grandparents lived on VE farm in Etne , Hordaland and I have a triangulation group for the cousins descended from them

I told Shelley she triangulated into that group very small so probably too far back to find. She replied my great grandmother was Anna VE ... so I found that we are 5th cousins once removed
Decided to investigating LuAnn, a new match with a surname of interest, Brekke




Another way to triangulate is to use other known relatives. Sometimes my brother and I got opposite side segments from Dad

These are my dad's matches: Everyone marked M for maternal matches my brother Shipley, but the P for paternal matches me



Since LuAnn matches Ship and Lester she must be maternal and since my brother matches Katy here, she is related on the WOLD line
M




(Chromosomes without matches removed)









Gunnar versus my brother


Top matches Dad has in common with Gunnar

Gunnar versus Kitty, no match on 2, match on 20

Dad's Matrix Matches


How to get a Chromosome Browser Results (CBR) file from Family Tree DNA for the DMT tool





DMT output as a CSV


DMT output as a CSV

Automated Triangulation Tool at GEDmatch.com


GEDmatch triangulation sorted by chromosome location

Gedmatch Triangulation for Dad sorted by Match Name
Cousin Katy

Gedmatch Triangulation for Dad cut and pasted to a spreadsheet then sorted by chromosome and start







Blog.KittyCooper.com
DNA Triangulation -2018 fall
By Kitty Cooper
DNA Triangulation -2018 fall
How to use triangulation to confirm DNA relatives
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