triangualtions

Triangulations

Triangulations are where you find 3 cousins that all match on the same segments of the same chromosome all descended from the same ancestral couple that are all related to each other. 7cM matches and above on these triangulations is considered actual proof! cM matches below that are tentative proof. Here is one way I recommend getting that data. It involves downloading your autosomal or family finder dna into Gedmatch.com. I recommend giving each kit a nickname that is unrelated to their name for privacy's sake. Then follow the below suggestions to the T. It will take a while for this to make sense and become easy.

1. Use the “Search all Gedcoms” tool to look up the Coate ancestor you are wanting to verify via your autosomal DNA.

2. Then use the Lookup User Tool – Type in gedcom number to get their Gedmatch number.

3. Check their Gedmatch numbers against your DNA with the One-to-One comparison tool. Change the fields for SNP’s to 200 and the cM’s to 5 is what I now recommend.

4. Place the results in a table like this one.

Gedmatch#	Name or email	Gedmatch#	Name or email	Chromosome	Starting Segment	Ending Segment	cM size	Snp's	Triangulations	Gedcom#	MCRA (Most Recent Common Ancestor)

A127179	dreg@yahoo.com	A102985	EP	17	8821603	11448590	10.1	895	T	7099180	William and Alice Calhoun
A092025	SM@gmail.com	A102985	EP	17	9077878	11448590	9.1	608	T	7099180	William and Alice Calhoun
A092025	SM@gmail.com	A102985	EP	17	9077878	11448590	9.1	608			Samuel son of Hugh Calhoun
A092025	SM@gmail.com	A810661	Hall	17	9116359	9944526	4.4	221			Joseph son of William Calhoun b 1633
A092025	Sm@gmail.com	A746916	DD Calhoun	17	9151937	9946822	4.3	215			Patrick son of James & Catherine Calhoun
A092025	SM@gmail.com	A127179	Sands	17	9613859	11718689	7.1	539	T	1871262	William and Alice Calhoun

5. Highlight your entire database. Sort the results by the chromosome, then by the starting segment.

6. Look through the list and see if any segments overlap with you and other cousins.

7. If you have a match between at least 3 of you, check each of their Gedmatch numbers against yours with the one-to-one comparison tool. They all have to have those same segments and chromosomes with each other for it to be a triangulation. One of the testers can't be a parent or child to another triangulated tester. One can be an Uncle or Aunt of the other. If memory serves, they also can't be siblings.

8. Also check to make sure that these cousins don’t match you with any other common ancestral couple between with the “Gedcoms” tool.

9. If the only ancestral couple you all descend from is the one you are studying and you all match each other on the same chromosome with some common segments, wallah! You have a triangulation which literally proves the most recent common ancestral couple (MRCA) you have in common.