Tuesday, June 29, 2021

Building your DNA competency

When you start working with DNA for your genealogy it may seem like there is too much to learn, but not so.  How deeply you want to expand your research using genetic genealogy will determine how you approach obtaining the skills required for analysis.  It is not the same for everyone.

There are generally 5 main reasons one might think about doing a DNA test.   

  1. I want to know my ethnicity
  2. I am interested in DNA for health reasons
  3. I am curious about what I will find out from knowing more about my DNA
  4. I am interested in using DNA to unravel a genealogical mystery
  5. I am interested in using DNA to validate my research tree

The competencies needed to be able to analyse your results for each of these are different, but they build on each other.  Points 1-3 require only a limited understanding DNA and its relevance for genealogy.  Whereas points 4-5 require a more detailed understanding of the DNA analysis process.  No matter what your goal, everyone needs to decide which DNA test is best for them.

This post seeks to outline the competencies you need to attain to build the DNA analysis skills you need for your research goal.  Not everyone needs to skill themselves in all of them.  Best practice suggests that you should start by looking at your results broadly, before diving into the detail of chromosome analysis.

Work through these lists systematically, tick off what you know!  Build your DNA analysis skills by understanding the basics before moving to the next level.


Before you test

If you are considering a DNA test, you need to understand which test is right for you depending on your DNA goal.  Make sure you consider the following points before testing.  Links in this section lead to blog articles that explain the points (adding links is an ongoing work in progress).  

  • I am aware of the limitations of DNA testing and its usefulness for genealogy
  • I have identified my DNA research goal/s
  • I am aware of the various companies offering DNA tests 
  • I am aware of the general principles of DNA inheritance to help me choose the right test
  • I am aware of the differences between the 3 DNA tests, yDNA, mtDNA and au/atDNA
  • I have a general understanding of how DNA testing companies identify ethnicities
  • I have a general understanding of how DNA testing companies provide health information

Starting to work with your DNA results - the basics
  • I have developed a pedigree for my known ancestry, to at least 16 x 2GGP's (if possible). 
  • I have developed a DNA Research Plan and documented my DNA research goals.
  • I understand the principles of DNA inheritance and how it is used in the analysis process.
  • I understand the differences between the 3 DNA tests, yDNA, mtDNA and au/atDNA and how to use them in the analysis process
  • I am aware that by working within a research framework and applying a DNA research methodology I will improve my success rate and productivity.
  • I understand the meaning of the key DNA terms and concepts - shared centimorgans (cMs), shared segments, shared matches, predicted relationships and cousinship.
  • I am able to use my testing company's system to identify and sort my autosomal DNA matches by shared cMs and identify shared matches.
  • I understand the limitations of 'shared matches' (called 'in common with' at FTDNA).
  • I understand how the shared cMs with my match can be used to predict possible relationships.
  • I am aware of how to use grouping and clustering techniques like the Leeds Method, to help classify my matches into potential grandparent groups.
  • I am aware of how to develop research trees using 'tree triangulation' to aid my genetic research.
  • I am aware of how to document and test relationship hypotheses using tools like 'What are the Odds @ DNA Painter' (WATO).
  • I am aware of the Genealogical Proof Standard, particularly as it applies to genetic genealogy.
  • I understand my responsibilities if I am administering a kit for someone else.
  • I am able to use my testing company's system to download my raw data.

Working with your DNA results - using chromosome analysis
  • I am competent in all aspects of 'the basics' when working with my DNA results (shown above). 
  • I understand there are 4 different types of DNA for research purposes, requiring different analysis techniques.
  • I have downloaded my raw data (autosomal only) from my testing site and uploaded it to other sites including GEDmatch, FTDNA, My Heritage and LivingDNA.
  • I understand the principles of DNA inheritance and how recombination impacts on chromosome analysis.
  • I understand the different inheritance factors for men and women for the X/23rd chromosome.
  • I understand the meaning of more involved DNA terms and concepts such as - recombination, Single Nucleotide Polymorphisms (SNP's pronounced snips), Fully Identical Regions (FIR), Half Identical Regions (HIR), Identical by Descent (IBD), Identical by chance/state (IBC/IBS), Identical by population (IBP).
  • I understand that there are two sides to each of the 23 chromosomes and how to allocate matches to either the paternal or maternal side.
  • I understand the difference between 'shared matches' and ‘shared segments on a chromosome’ for autosomal analysis.
  • I understand the differences between ‘in common with - on a segment (sometimes called overlapping segments)’ and 'segment triangulation'.
  • I understand the meaning of the term 'triangulated group' and why it is important for autosomal analysis.
  • I have developed a method for organising, storing and searching my DNA matches by chromosome, shared cMs and potential ancestor groups (including clusters and triangulated groups).
  • I am aware of how to use 'triangulated groups' to identify potential shared ancestors by developing research trees to aid my genetic research.
  • I understand what constitutes 'tentative' and 'confirmed' DNA matches when identifying potential shared ancestors.
  • I am able to identify segments inherited from a specific ancestor or ancestral couple and apply them to a chromosome map, such as DNA Painter.
  • I am aware of the limitations of tools like WATO when testing relationship hypotheses and understand the need for 'segment triangulation' to confirm relationships beyond 3rd cousins or where no paper trail exists.
  • I have read and understand the Genealogical Proof Standard, particularly as it applies to genetic genealogy.


Doing more with your DNA results - advanced techniques 

Once you are competent in all aspects of 'the basics' and 'using chromosome analysis' you could consider more advanced DNA techniques.  Tackling these tools/techniques should only be attempted once you are competent in all the above.
  • Phasing techniques
  • Using Gedmatch tools including Evil Twin, Lazarus
  • Visual Phasing
  • Inverted Mapping
  • Inferred Mapping
  • Deductive Mapping (inferred inversions)
  • Developing chromosome maps for your ancestors
  • DNA Reconstruction techniques

Further Reading

Read more about the DNA Research Framework and Methodology here.

Christine Woodlands has developed an AncestryDNA course that addresses all the steps outlined in 'the basics' section.  It was recently delivered at the Society of Australian Genealogists (SAG).    Read more about the course on Mossie's Musings and check the SAG website for possible future delivery dates.

Veronica Williams is in the process of developing a complimentary course for 'chromosome analysis', expected to be delivered through SAG in 2022.

Join the International Society of Genetic Genealogy - it's free!  Please consult the ISOOG website and the ISOOG wiki for more information, including their helpful Genetics Glossary.