DNA – a powerful tool for the 21st century genealogist

DNA is a powerful tool.  It can solve family puzzles, and may be used to extend the family tree.  Millions of Americans have already taken a DNA test, and Ancestry.com recently boasted they now have 1.4 million testers in their AncestryDNA database.  They are joined in their DNA endeavors by 23andMe and FamilyTreeDNA.

So what’s all the hoopla about and how can DNA testing help you?

Types of DNA testing
There are three types of DNA tests:  Y-DNA, mtDNA and autosomal DNA.

Many people are familiar with the Y-DNA test, which is used to trace one’s paternal line.  The Y-DNA test may only be completed by a male, as it tests the Y chromosome which only men carry.  It looks at the DNA which a man inherits from his father’s father’s father and so on.  Because Y-DNA has few mutations, it can be used reliably to determine if two men share a common male ancestor.  This is extremely helpful when researching two or more men who lived in the same town, share a common surname and the paper trail has not been able to confirm or rule out a relationship.  By testing male descendants of the research targets, one can know with certainty if the two are related.

Mitochondrial DNA testing is similar to Y-DNA testing, in that it focuses only on one line of your family – the maternal line – by looking at the mitochondrial DNA (or mtDNA) which a person inherits from his or her mother’s mother’s mother, etc.   Both males and females may complete a mtDNA test.  However, mtDNA’s use is often limited unless one has a solid line in which maiden names of female ancestors are known.   Because of this, mtDNA is most often utilized to determine if two females share a common ancestor.

Autosomal DNA
Autosomal DNA is one of the most powerful tools to unravel genealogical mysteries.  While Y-DNA and mtDNA limits testers to information on their paternal and maternal lines, autosomal DNA looks at the DNA we inherit from our remaining ancestors.  By comparing autosomal results to other testers, one can identify cousins with whom we have common ancestors.  If those cousins are open to collaboration on their research, long-standing brick walls may begin to fall down.  For an example of how I used autosomal DNA to find the maiden name and parents of my 4th great grandmother, click here.

While DNA testing can be an awesome tool, it is not a replacement to old fashioned genealogical research.  Beginners to genealogy should still focus their initial efforts on compiling their family tree using traditional research methodologies.  The more information that can be compiled the better, as it will enable you to compare your family with tree others, identifying common surnames and common locations where ancestors previously resided.

Getting more than you bargained for
Those completing DNA testing must also be prepared for potential surprises.  Adoptees are now turning to DNA testing to help narrow the search for potential birth parents.  Testing your DNA makes it possible for family members such as unknown siblings to contact you.  If one of your parents has children from a previous relationship that have not been disclosed to the family, contact by these older, unknown siblings may stir up troubling emotions.

Another scenario in which testers must consider is the possibility of non-paternity events, in which the father who raised an individual is not the tester’s biological father.  Such discoveries are often painful and difficult to work through, both for the tester and for any living family members that may be impacted by the discovery.

Still ready to proceed?
If you are ready to embark on the DNA journey, the next step is selecting a testing company. Below is a comparison of the three major companies who provide DNA testing for genealogical purposes and the types of tests performed.

AncestryDNA FamilyTreeDNA 23andMe
Autosomal X X X

Other considerations
Another factor to consider when choosing a testing company is the ease of use.  I have completed autosomal testing with all three companies, and have found AncestryDNA to be the simplest to use.

The beauty of Ancestry is that a large percentage of testers have public family trees, enabling you to independently compare your tree to theirs to see if you have a common ancestor.  For most people, AncestryDNA is a good place to start.  A bonus with AncestryDNA is that you may download your raw data or results and then submit it to FamilyTreeDNA, allowing you to determine matches with both companies. If you decide to contact matches, it is completed through the Ancestry message portal.

FamilyTreeDNA is the leader in reporting features.  Advanced users can use the site’s chromosome browsers to see the location of the DNA match on the chromosome.  It also permits users to filter matches by surname, by shared matches, and more.  While FamilyTreeDNA does allow testers to compare family trees, this feature is not nearly as robust or as user friendly as that found on the Ancestry site.  Contact with matches is completed via email.

For those wishing medical information as well as DNA testing for genealogy, 23andMe may be the preferred choice.  However, most will find the ability to collaborate with matches far superior with both FamilyTreeDNA and AncestryDNA, making them more suitable options (and for half the cost!).

Additional information
For more detailed information on genetic genealogy, the following excellent resources are available:

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One Response to DNA – a powerful tool for the 21st century genealogist

  1. Barbara says:

    Great article! Thanks! I have tested my autosomal DNA with Ancestry and also find the trees very helpful. Have found 3 or 4 fourth cousins through some detective work with my DNA cousin’s trees. I have tested my mtDNA and my brother’s Y-chromosome DNA on FamilyTreeDNA but have not really gotten familiar enough with the site to get much done (on my to-do list, along with transferring my autosomal DNA raw data from Ancestry to FamilyTree). I am an intermediate genealogist but a tech newbie, so one step at a time…..

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