Outline of Segmentology

The outline below shows the topics I plan to cover in this blog. Some are hyperlinked to the blog post. This outline may be adjusted from time to time as new topics come up.

[01] Introduction and Disclaimer – no contract, compensation, or allegiance to any company. Unpaid volunteer at GEDmatch. An FTDNA Surname Project Admin since 2002. Statements/opinions are my own.

[01A] Getting Started with Autosomal DNA Part I

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

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

[03A] Fuzzy Data, Fuzzy Segments – No Worry

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

[05A] Segments: Bottom-Up

[05B] Segments: Top-Down

[06A] Segment size vs cousinship – Mathematical averages vs Range

[06B] Segment size vs cousinship – Curves in practice (Blaine’s data)


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

[07B] Ancestors – “Sticky Segments

[07C] Proof of Stick Segments

[08] Triangulation Concept – no genealogy (emphasis on tool)

[09] Benefits of Triangulation

[10] How To Triangulate: Collect, Arrange, Compare/Triangulate

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

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

[10C] Triangulation: CA vs MRCA – diagrams

[10D] Triangulation: Getting Past Brick Walls

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

[11A] Does Triangulation Always Work?

[11B] Does Triangulation Work?

[12] Triangulation “Rules

[13] Triangulation vs IBD – Chicken/Egg

[13] Small Segments and Triangulation

[14] Triangulation vs Phasing

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

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

[15B] Jigsaw puzzle

[15C] Chromosome Mapping: Finding NPEs

[15D] Estimating Distant Cousinships

[16] Segment analysis

[16A] Parents

[16B] Siblings

[16C] Close relatives

[16D] Endogamy I – Shared DNA

[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

[19] Glossary of Terms (cf ISOGG)

[20] Links

[21] Misc

[21A] Why Upload to GEDmatch or FTDNA?

[99A] Anatomy of an IBS segment by Ann Turner 20151002

3 thoughts on “Outline of Segmentology

  1. 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


  2. 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 1 person

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