Re: Triangulated DNA matches and Pile-up Areas #dna


Lee Jaffe
 

I very much appreciate the suggestions and comments I've received here and privately.  I think I understand the approaches suggested, have looked at additional guides and sources, and have pivoted, I hope, to a better strategy. 

Before getting into the new approach, I wanted to respond to one note which posed whether this was the best use of my time and energy.  Honestly, I don't know and I hope that exchanges here can help me figure this out before I go to far.  My goal is to extend my family research beyond what I've been able to achieve so far through conventional or traditional methods.  I have a fairly well-developed tree,  which goes back in a couple of cases 9 generations.  But there are some mysteries therein, such as the parentage of my 3x great-grandmother or what happened to my great-grandparents' newly discovered siblings and their descendants. I am hoping that triangulation will help me distinguish DNA matches into groupings according to possible common ancestors with the goal of placing them in my family tree when I follow up with traditional methods.

Therefore, following new sources, I have downloaded my match data from FTDNA, 23andme, and MyHeritage.  I've started to filter and sort the entries by Chromosome number and starting position in order to identify potential triangulated matches.  But the number of entries (~150K lines) is cumbersome and daunting.  Just starting with the beginning of the MyHeritage data, I have more than 100 matches starting at the same position on Chromosome 1.  Given that MH allows you to compare only 7 matches at a time in its Chromosome Browser, I've been trying to find ways to prioritize which would be most likely and most useful.  It's not straightforward.  For instance, I've discovered that a batch of segments with the same beginning and ending location do not triangulate, at least not according to MyHeritage's Chromosome Browser even though it says it allows for segments as small as 2cM.
Chr# Start Location End Location Start RSID End RSID cMs SNPs
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
1 752,566 4,007,008 rs3094315 rs7519349 7.2 1920
Plugging combinations of the above matches from MH into its Chromosome Browser gets a "no triangulated segments" result.  Note: all are above the 7.0 cM threshold recommended in the comments I received. 


Then I looked for other groupings featuring larger segments and had better success with those with segments larger than 10cM.  For instance, in the following batch, all but two of the matches triangulate with each other.  A and F are the exceptions, even though the numbers for A are identical to B, as is F to E.  

A 1 10,825,577 17,954,411 rs11121615 rs12060961 14.6 4096
B 1 10,825,577 17,954,411 rs11121615 rs12060961 14.6 4096
C 1 10,825,577 18,279,185 rs11121615 rs709362 15.3 4352
D 1 10,825,577 18,528,026 rs11121615 rs9725311 16.1 4608
E 1 10,825,577 18,528,026 rs11121615 rs9725311 16.1 4608
F 1 10,825,577 18,528,026 rs11121615 rs9725311 16.1 4608
G 1 10,825,577 19,022,911 rs11121615 rs12563055 17.7 4992
H 1 10,825,577 19,136,610 rs11121615 rs11261075 18.4 5120

I feel like I need to understand why I'm seeing results like this before going much further down this path.  As always, I appreciate your help.

Thank you,

Lee David Jaffe
===============
Surnames / Towns:  Jaffe / Suchowola, Poland ; Stein (Sztejnsapir) / Bialystok and Rajgrod ; Roterozen / Rajgrod ; Joroff (Jaroff, Zarov) / Chernigov, Ukraine ; Schwartz (Schwarzstein) / Ternivka, Ukraine ;  Weinblatt / Brooklyn, Perth Amboy, NJ ; Koshkin / Snovsk, Ukraine ; Rappoport / ? ; Braun / Wizajny, Suwalki,  Ludwinowski / Wizajny, Suwalki

 

Join main@groups.jewishgen.org to automatically receive all group messages.