Outline of Segmentology

The outline below shows the topics I have posted [with hyperlinks to them] and some that plan to cover in this blog.

[00] Segmentology: Outline of Segmentology (14 Apr 2015 to 26 Mar 2020)

[01] Introduction and Disclaimer – I became an engineer in 1966; a Naval Officer in 1967; a genealogist in 1974; a registered Professional Engineer in 1980; a genetic genealogist (when I started a Y-DNA surname project) in 2002. I have bought original DNA kits at FTDNA (Y-111 and Big-Y, SNPs, FMS, atDNA), 23andMe, AncestryDNA, Genographic, Genos (exome), LivingDNA and MyHeritage; and uploaded to Y-Search, mitoSearch, NIH, GEDmatch, and DNA.Land. I lecture on genealogy and DNA to genealogy groups and conferences. I have no contract, compensation, or allegiance with any company. I am an unpaid volunteer at GEDmatch; a Surname Project Admin at FTDNA; and a long-time subscriber/researcher at Ancestry and FamilySearch. Statements/opinions are my own.

[01A] Getting Started with Autosomal DNA Part I (22 Nov 2015)

[02] What is a segment? – Ancestral (true) Segments vs Shared (computer) Segments (7 May 2015)

[03] Measuring Segmentsbp (or Mbp); cM; SNP (13 May 2015)

[03A] Fuzzy Data, Fuzzy Segments – No Worry (30 May 2015)

[04] How Ancestral segments are formed – Recombination & Crossover Points

[05] Segments

[05A] Segments: Bottom-Up (24 May 2015)

[05B] Segments: Top-Down (1 Jun 2015)

[05C] CA and MRCA (2 Jan 2016)

[05D] Crossovers by Generation (2 Feb 2016)

[05E] Anatomy of a TG (5 Feb 2016)

[06] Segment size vs cousinship – Mathematical averages vs Range (Blaine’s data)

[06B] Segment Size vs Cousinship –Chart Needed –Estimated Curves (7 Nov 2015)

[06C] In Defense of Small Segments (21 Jan 2020)

[06Z] VUCA DNA (24 Aug 2015)

[07A] Ancestors – The Porcupine Chart (Biological vs Genetic Ancestors) (7 Aug 2015)

[07B] Ancestors – “Sticky Segments

[07C] Proof of Stick Segments (16 Nov 2015)

[08] Triangulation Concepts

[08A] Your TGs are Pretty Unique! CONCEPT (7 Sep 2017)

[08B] The MRCA Knothole! CONCEPT (9 Sep 2017)

[08C] MRCA Knothole Guidelines. CONCEPT (10 Sep 2017)

[08D] Using a Group Common Ancestor. CONCEPT (20 Jun 2020)

[09] Benefits of Triangulation (9 May 2015)

[10] How To Triangulate: Collect, Arrange, Compare/Triangulate (11 May 2015)

[10A] How To Triangulate: GEDmatch; 23andMe; FTDNA – screen shots

[10B] Triangulated Groups – Assign and Determine Ancestors – genealogy, admixture

[10C] Triangulation: CA vs MRCA – diagrams [see [05C]

[10D] Triangulation: Getting Past Brick Walls

[11] Why Triangulation works (1 vs 2 chr; IBD segs)

[11A] Does Triangulation Always Work? (10 May 2015)

[11B] Does Triangulation Work? (19 Oct 2015)

[11D] Are Overlapping Segments Triangulated? (15 Apr 2020]

[12] Triangulation “Rules

[13] Triangulation vs IBD – Chicken/Egg

[13A] Small Segments and Triangulation (30 Sep 2015)

[14] Triangulation vs Phasing

[15] How Triangulated Groups (TGs) play out in practice

[15A] Understanding and using TGs (18 Sep 2016)

[15B] The Attributes of a TG (19 Sep 2016)

[15C] Chromosome Mapping – physical (stone wall, no gen); link ancestors to TG segments)

[15D] Jigsaw puzzle

[15E] Chromosome Mapping: Finding NPEs

[15F] Estimating Distant Cousinships

[15G] A Targeted Process at AncestryDNA (20 Oct 2016)

[16] Segment analysis

[16A] Parents

[16B] Siblings

[16C] Close relatives

[16D] Endogamy PART I – Shared DNA (2 Dec 2015)

[16E] Endogamy PART II – One Segment from One Ancestor (5 Jan 2016)

[17] Spreadsheets

[17A] Format – what data

[17B] Recommendations

[17C] Getting data

[17D] Updating data

[17E] Tips on using a spreadsheet as a tool

[18] Pile-ups: Small segments; TG segments (7 Oct 2015)

[19] Clustering

[19A] Think Icicles! (30 Oct 2018)

[19B] Icicles – Part 2 and Match Clustering (8 Jan 2019)

[19C] Shared Clustering – A Great Tool! (29 Nov 2019)

[19D] Walking the Clusters Back (1 Dec 2019)

[19E] Walking The Clusters Back II (5 Dec 2019)

[19F] Walking the Clusters Back III [14 Dec 2019)

[19G] A Unified Theory of Genetic Genealogy (16 Dec 2019)

[19H] Let the Matches Tell Us the Cluster Common Ancestor (20 Jun 2020)

[19I] Easy Manual Clustering at AncestryDNA (1 Jul 2020)

[19J] Segment-ology: Use Clusters! (5 Jul 2020)

[See also these TIDBITS]

[22Z] Match Clusters – Chicken or Egg? TIDBIT (11 Feb 2019)

[22AA] Confessions of a Match Clusterer TIDBIT (14 Feb 2019)

[22AB] Walking the Clusters Back TIDBIT (14 Feb 2019)

[22AC] Match Cluster Report 1 (14 Feb 2019)

[22AD] D I Y Clustering TIDBIT (18 Feb 2019)

[22AE] Clusters Link to TGs and an Apology TIDBIT (22 Feb 2019)

[22AF] Clustering Programs TIDBIT (4 Apr 2019)

[22AP] Extending the MRCA of a TG through Clusters TIDBIT (18 Nov 2019)

[22AQ] Grouping Matches – Try It! TIDBIT (28 Nov 2019)

[20] Links

[21] Misc

[21A] Why Upload to GEDmatch or FTDNA? (11 Jun 2015)

[21B] Getting Started with GEDmatch (19 Sep 2017)

[[see also [22T] First Time at GEDmatch TIDBIT (1 May 2018)]]


[22] Segmentology TIDBITs

[22A] Crossover and Segment Formation TIDBIT (2 Jan 2017)

[22B] Number of Matches on a Segment (or TG) TIDBIT (2 Jan 2017)

[22C] Roughly Right is OK for Genealogy TIDBIT (2 Jan 2017)

[22D] Only One Comparison Needed to Add a Segment to a TG TIDBIT (2 Jan 2017)

[22E] Save the Clues TIDBIT (2 Jan 2017)

[22F] Walking the Ancestor Back TIDBIT (4 Jan 2017)

[22G] Uploading to GEDmatch TIDBIT (19 Jan 2017)

[22H] One Segment at a Time TIDBIT (18 Feb 2017)

[22I] Format for AncestryDNA Notes TIDBIT (7 May 2017)

[22K] Amount of DNA vs Number of Matches TIDBIT (17 May 2017)

[22L] Using a Child to Determine the Side TIDBIT (12 Jul 2017)

[22M] Triangulation at 23andMe TIDBIT (20 Jul 2017)

[22N] A Triangulation Overview TIDBIT (28 Jul 2017)

[22P] Using AncestryDNA Notes TIDBIT (9 Sep 2017)

[22Q] Make a Resolution to Contact Your Matches TIDBIT (7 Jan 2018)

[22R] When a Plan Comes Together TIDBIT [17 Mar 2018)

[22S] Contact Your Match Soon TIDBIT (15 Apr 2018)

[22T] First Time at GEDmatch TIDBIT (1 May 2018)

[22U] Confusion about Base Pairs TIDBIT [2 May 2018)

[22V] AncestryDNA Search on Notes TIDBIT (1 Jun 2018)

[22W] Shorthand ID for Common Ancestors TIDBIT (2 Feb 2019)

[22X] Shorthand ID for Triangulated Groups TIDBIT (2 Feb 2019)

[22Y] The Fundamental Building Blocks of Genetic Genealogy TIDBIT (3 Feb 2019)

[22Z] Match Clusters – Chicken or Egg? TIDBIT (11 Feb 2019)

[22AA] Confessions of a Match Clusterer TIDBIT (14 Feb 2019)

[22AB] Walking the Clusters Back TIDBIT (14 Feb 2019)

[22AC] Match Cluster Report 1 (14 Feb 2019)

[22AD] D I Y Clustering TIDBIT (18 Feb 2019)

[22AE] Clusters Link to TGs and an Apology TIDBIT (22 Feb 2019)

[22AF] Clustering Programs TIDBIT (4 Apr 2019)

[22AG] ThruLines Finds Your Common Ancestors TIDBIT (29 Jul 2019)

[22AH] Help ThruLines by Adding Children and Grandchildren TIDBIT (29 Jul 2019)

[22AI] ThruLines Has Xray Vision TIDBIT (29 Jul 2019)

[22AJ] ThruLines Helps with Y-DNA and mtDNA TIDBIT (29 Jul 2019)

[22AK] A Few ThruLines Are False, and Some Are Misleading (29 Jul 2019)

[22AL] Add ThruLines Info Into Match Notes TIDBIT (29 Jul 2019)

[22AM] Use Match Notes from ThruLines to Identify Clusters (29 Jul 2019)

[22AN ] ThruLines and Clusters and Snowballs (29 Jul 2019) *

[22AO] How Does ThruLines Work TIDBIT (1 Aug 2019)

[22AP] Extending the MRCA of a TG through Clusters TIDBIT (18 Nov 2019)

[22AQ] Grouping Matches – Try It! TIDBIT (28 Nov 2019)

[22AR] AncestryDNA ThruLines Missing Out TIDBIT (26 Mar 2020)

[22AS] Download Your AncestryDNA Matches in 10 Minutes! TIDBIT (9 Apr 2020)

[22AT] Clusters at Brick Walls TIDBIT (8 May 2020)

[22AU] Using Ethnicity to Identify a Cluster TIDBIT (12 Jun 2020)

[22AV] Find AncestryDNA Matches with Common Ancestors TIDBIT (8 Aug 2020)

[23] Ancestors

[37P] Breaking Thorough a Brick Wall (5 Aug 2019)


[25] Glossary of Terms (cf ISOGG)


[99A] Anatomy of an IBS segment by Ann Turner  (2 Oct 2015)

[99B] Advanced Genetic Genealogy Book (6 Apr 2019)


9 thoughts on “Outline of Segmentology

  1. This is great! I just finished NGS’s online Genetic Genealogy course and needed more detail. They included your website in their list of Recommended Reading — my thanks to the course designer for directing me to you, and my thanks to you for a great series of blog posts!


  2. Jim, a thousand thanks for your work on this, which I was introduced to through a superb course by Maurice Gleeson. Thanks also for being the inspiration for GedMatch.com’s Tier 1 Utility “Triangulation Groups – Beta.” After getting hooked on its great functionality, I note that it has been down for the last 5 days or so. Are you (or they) working on it?


    • Maureen, Thanks for your kind words. The Tiangulation programs at GEDmatch are a great way to start your TGs and mapping. But after that start, I just add new Match-segments to my spreadsheet and check them against overlapping segments which are already there. I am not working on the software, maybe the tech guys are. Jim


  3. Jim, I know you have ‘spreadsheets’ on your to-do list, but do you have yours or a dummy version of it (stripped of your own data) available anywhere for a peek at? I am in the early stages of the process and I can see it will take me a couple years to re-invent my own wheel. I’m particularly interested in how you organized your family tree info to facilitate searching for MRCA with matches, and organizing data for triangulating.

    Liked by 2 people

  4. I am so thankful for all of your explanations on all of your blogs I am learning so much. I am so grateful to you for sharing your expertise with all of us because it becomes so frustrating many many thanks for all of your hard work and sharing of your expertise


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