15 April 2013

Useful DNA Tests for Genealogy

This article is available as a PDF file with permission granted to freely copy this document in its entirety for educational purposes.

Genealogical DNA Tests

There is a lot of confusion on how to use DNA test results for genealogical research and which tests are useful for what purpose. Some of that confusion comes because the terminology is new to us. Spending our money wisely on the right DNA test means taking the time to understand the terminology, what each particular test can show us, and how that applies to our family research.

In many situations a DNA test may be the only way to find evidence to support a theory of kinship. In other situations a DNA test will not help at all. Consulting a genetic genealogist can help you decide what may work for you if you don’t want to spend the time to study this yourself.
Before ordering any DNA test you should know:

1. What is it you are trying to learn or prove?

2. Which DNA test will provide the information needed?

3. Who is alive in the particular line in your family tree who has inherited the right DNA segment to provide evidence for what you want to learn?

Reading articles and blog posts by genetic genealogists can help us answer the second question. Use a search engine to find online articles, blogs, and websites of genetic genealogists.

DNA Analysis for Genealogical Purposes

All of the DNA tests described below will provide results that may be useful for a historical or genealogical research project—your research project. But the results must be carefully analyzed and correlated with your evidence from traditional genealogical research before a conclusion is reached.

As you find a new document related to your ancestor you take the time to learn what the contents of that document mean so that you can interpret the information correctly in relation to your family. You will have to do the same to make use of results from a DNA test. It won’t be like the CSI shows on TV where an answer magically appears in a matter of minutes. You will have to study how to use the test results to make the most of this exciting technology and the information it provides.

Autosomal DNA Tests
(Family Finder, Relative Finder, AncestryDNA, Geno 2.0, and others)

Autosomal DNA tests (atDNA) have been available for some time, but it is only in the last five or so years that they have become really useful for genealogical purposes. An autosomal DNA test can be performed on a man or a woman. It tells us something about many of our ancestors, not just the direct paternal or maternal line.

The results of your atDNA test can be compared to others who have tested and mathematical algorithms predict how closely you may be related based on how much DNA is shared. Using these test results to the fullest will require some time and study. But amazing discoveries may be made about the last five or so generations of the family of the person whose DNA is tested. Predictions related to ancestral populations, such as Vikings and others, are still being studied and there is more to learn.

Y-DNA Tests

Y-DNA tests have been used for genealogical purposes since about 2000. A Y-DNA test can only be performed on men and only tells us about that man’s paternal line. The basic Y-DNA tests offered, referenced by the number of markers tested such as “37-marker test,” usually gives you information that can determine if two men have a common ancestor within a genealogical time frame or not. The test cannot usually indicate any specific relationship between those two men, such as father-son.

Mitochondrial DNA Tests

Mitochondrial DNA tests (mtDNA) began to be used for genealogical purposes a few years after Y-DNA. An mtDNA test can be performed on a man or a woman and only tells us about that person’s maternal line. Changes in mitochondrial DNA happen at a rate that may make this more difficult to use except for specific genealogical purposes. Discussing your particular problem with a genetic genealogist and using a pedigree and/or descendant chart can help determine if an mtDNA test can help you gather evidence to solve a particular problem.

Use of DNA Tests: Scientific vs. Genealogical

Scientists use these same or similar DNA tests to study populations and ancient migration paths and many other things. When scientists talk about “genetic ancestry” they usually mean deep ancestry, tracing the migration of humans thousands of years ago. Scientists may disagree on exactly what can and cannot be proven with the knowledge we have today. That is how scientific research works—someone has a theory, experiments or tests are performed, results are analyzed, and findings may cause a new theory to be formed or the old theory may be supported. Free and open discussions bring new evidence to light. As new evidence is found our understanding may change. This sounds a lot like genealogical research to me.

Most genealogists are not as concerned about our deep ancestry so we aren’t as concerned with the scientific debates. We want to know more about our ancestors within the last few hundred years. A DNA test is likely to help you discover more about your family. But it will require you to study and learn more than you may know now. As more people test we will learn more and we will learn new ways to apply this new knowledge.


Genetic genealogy is cool, cutting-edge science.
But you have to learn how it works
to make the most of this new technology.
When reading about genetic research be sure you
understand whether genealogical research
or scientific research is being discussed.
Terms that sound similar may be used in a
slightly different way by the two groups.

What doesn’t help much with scientific research may be exactly what a genealogist needs.



To cite this blog post:
Debbie Parker Wayne, "Useful DNA Tests for Genealogy," Deb's Delvings Blog, posted 15 April 2013 (http://debsdelvings.blogspot.com/ : accessed [date]).

© 2013, Debbie Parker Wayne, CG, CGL, All Rights Reserved

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