April 4, 2019

D is for… DNA

by admin in Uncategorised

DNA testing has revolutionised the world of genealogy over the past few years and become an essential tool in the genealogist’s toolbox.  Here is a list of some of the reasons to DNA test and the ways it can help with your genealogical journey:


You can learn about your ethnic make-up via ethnicity estimates provided by the different companies (autosomal tests only). While ethnicity estimates are the most well-known aspect of DNA test results, they are not the most useful for family history – it’s the DNA match list you also receive as part of an autosomal test that you should focus on for genealogical purposes.  It’s also important not to take ethnicity estimates too literally; they are called estimates for a reason.

Surname Studies

If you are interested in researching a particular surname or want to do a one-name study, it’s worth considering Y-DNA testing. Y-DNA is passed down only by males along the direct paternal line (father’s, father’s, father’s line) so only men can take the test.  You don’t need to limit yourself to your own Y-DNA line, however, as Y-DNA reaches much further back in time than autosomal and so long as you can find an appropriate tester for the line you’re interested in, it shouldn’t matter if that man is your first or fifth cousin.  Only FTDNA offers a Y-DNA matching database and projects.


You can leave a legacy for your descendants by DNA testing. Testing our older generations now while we can is crucial as they have more of our ancestors’ autosomal DNA than we do – parents have double, grandparents have triple and so on.

Testing Hypotheses

If documentation doesn’t exist to prove a specific relationship DNA may be able to help. Depending on the relationship it’s possible to use autosomal DNA, Y-DNA or Mitochondrial DNA to test a hypothesis.  Remember autosomal DNA is limited to approximately the last 5-7 generations so if you are looking for evidence for a hypothesis about a 7th great grandparent it’s best to use Y-DNA or MtDNA depending on which is applicable but if, for instance, you want to check your great grandfather really was your great grandfather then autosomal is by far the most useful way to test a closer hypothesis.

Chromosome Mapping

This is assigning segments of your DNA back to specific ancestors or ancestral couples. In order to undertake chromosome mapping, you have to be able to identify relationships with your DNA matches because it’s the segments you share that you can map back to your shared ancestors.  It’s interesting and exciting to know which pieces of your DNA came from which of your ancestors but it’s also very helpful on a practical level as it can aid you in working out how new matches fit in when they share a segment you have already mapped.  I recommend using DNA Painter to map your chromosomes – be warned that this can be addictive once you get started!

Connecting With New Cousins

Finding and connecting with living cousins can be one of the most exciting and rewarding benefits of DNA testing. Your new cousins may have family stories, photographs, memorabilia etc they can share with you so it’s always worth reaching out.  Many don’t respond but those that do make it all worthwhile and I’ve had replies up to five years after I first sent a message!

Adding New Branches To Your Tree

Identifying new cousins via DNA allows you to add new collateral lines (descendants of siblings of ancestors) to your tree. It’s important to build your collateral lines as far, wide and deep as you can as this is a fantastic reference for working on your cousin matches.

Breaking Brick Walls

We all want to break our stubborn brick walls but some simply cannot be broken using conventional research no matter what we try. Your DNA matches, especially your more distant ones, may provide the clues you need to break down your longstanding brick walls.

Solving Mysteries

There are some genealogical puzzles that traditional research can never solve because the documentation simply doesn’t exist to do so. DNA has opened up a whole new world of possibility for those with previously unsolvable mysteries e.g. adoption, unknown parentage, unknown grandparentage and all manner of unknown ancestor mysteries.  Using cousin matching it is now possible to solve these puzzles and identify unknown mystery ancestors.

Verifying Your Family Tree

When you match with cousins who share the same ancestors, you are verifying your family tree. You may think this is just telling you what you already know but in fact, it’s telling you what you think you already know is actually correct!  It’s priceless verification to add to your paper trail evidence because no matter how good a researcher you are and how well-sourced your tree is, it can still always contain errors through no fault of your own.  This is my personal favourite reason for DNA testing as I’ve been building my family tree using record sets over many years and to get confirmation from DNA matches that I genuinely share segments of DNA with cousins whose paper trails contain the same ancestors as me is gold dust evidence that my tree is accurate.  Be aware that many of us will find some lines on our trees are incorrect via DNA testing as well so it works both ways.

More and more people are DNA testing all the time and the usefulness of DNA testing for genealogy increases exponentially as the databases expand.  It’s very important to understand both the benefits and the limitations of the different tests and to be prepared for the possibility of surprises.  We must all be aware that DNA tests could provide a shock in the form of close family members we never knew existed or finding out we don’t descend from the people we thought we did.  Also while DNA itself cannot lie (as is often repeated) it can be misinterpreted so it’s imperative to learn as much as you can about how to work with your DNA tests and matches before coming to premature conclusions.  Finally DNA alone cannot tell you much at all; you have to use it in conjunction with traditional research methods to get the most out of it.  Traditional research and DNA are a perfect complement to each other and together can greatly boost your family history research.

Michelle Leonard M.A. PgCert
Professional Genealogist, Genetic Genealogist, Researcher & Historian

Genes & Genealogy ©2019

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