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How DNA Tests Helped Me with Genealogy!

By Jason Gavin, Special Collections Librarian

DNA_OverviewI’ve discussed some of the various kinds of DNA tests available before. Recently I was discussing with family my experience with the DNA test compared with the National Genographic test -both of which I’ve taken- and thought I’d share my experience. Of course, ultimately which test you find most useful or interesting will depend on what you, personally, are hoping to get out of the test.

For myself, I find Y-DNA/ Mt-DNA tests to be far more interesting than Autosomal tests.   I found the autosomal tests (like the one Ancestry offers) kind of vague. Basically, it will show you matches between your DNA and other Ancestry users with a % confidence rate (90% likelihood this is a 3rd cousin, for example). You could then go to that person’s family tree (if it’s not private) and figure out how you match up. That’s assuming of course that their family tree has correct information, which unless you’ve verified their research is a big assumption. It’s kind of neat, but I’ve yet to see it lead to a breakthrough in anyone’s “brick wall” ancestor.

The other thing the autosomal DNA tests offer is an “ethnicity estimate”. That takes your DNA and compares it to samples from all around the world, and tells you what population you most closely match. So for example, it might say “Your DNA looks like your 54% British Isles, 20% German, 10% Native American…” and so on. But remember, the autosomal tests are only good for up to 6 generations, so it doesn’t really tell you anything about the ancient origins or ancestral “homeland” of your direct paternal or maternal lines. For that, you’d want a Y-DNA and/or Mt-DNA test.

I myself was most interested in the ancient DNA information. Especially because on both my father’s and mother’s side, I haven’t been able to trace the families “across the pond” for the direct maternal line or direct paternal line. The Y-DNA and Mt-DNA helped shed some light on this. So, even though these tests didn’t connect me with any specific people, I learned that on Dad’s side, we have a DNA marker that is found in Northwestern Irish families traditionally connected with the Ui Neal dynasty of Irish kings – and on Mom’s side, my haplogroup is a quite rare one that is a remnant from the first humans to venture into Europe as hunters/ gatherers– long before the invention of agriculture and prior even to the last ice age! Cool stuff, huh?

So for me, my money is on the National Genographic test. It gives you Y-DNA and Mt-DNA, as well as autosomal, and you can transfer your results to FamilyTree DNA for free!


DNA tests for Genealogy

By Jason Gavin, Special Collections Librarian

DNA testing offers the modern genealogist an important and powerful tool that can provide unique information never available to previous generations of genealogists. In fact, there are so many companies offering DNA tests on today’s market, it can be somewhat daunting to know where to begin. In short, the answer to the question – “what kind of DNA test should I take?” can be answered by asking, “What kind of information are you hoping to get?” Below I’ll review some of the different types of genealogical DNA tests out there, and explain some of the pros and cons of each.

Y-DNA tests:

This test examines DNA found on the Y-chromosome. The Y-chromosome is one of the sex chromosomes that determine the gender of humans. Women of have an “XX” set of sex chromosomes while Men have an “XY” combination. Consequently, one drawback of the Y DNA test is that only males can take it, and it only traces a direct paternal line. It will give you information on your father’s father’s father, and so on, but no information about any females in your line, as the Y chromosome is only inherited by males. This means a Y DNA test can be especially useful for tracing surname history and origins, as surnames are also usually inherited along a direct paternal line.

Two males descended from the same male ancestor will have inherited the same DNA marker. That means that if you or a male relative and another person have the same marker 40 generations back, this test will let you know. One interesting consequent of this is what’s called the “Genghis effect”. In researching DNA dispersal through populations, it was discovered that a large proportion of the male population in Central Asia and beyond carry the same particular Y- DNA marker, meaning, they are all descended from the same single male. Further research concluded this was probably Genghis Khan, who conquered much of Asia and whose sons (who continued ruling in various parts of the continent) would have continued passing on this marker.

In addition, Y-DNA tests can provide “deep genealogical” information. Humans began migrating out of Africa beginning as early as 60,000 years ago, but they did so in waves. Often, there would be a wave of migrations to somewhere out of Africa – say the central Asia for example – and that wave would stay put for thousands of years, before a sub group would split of and travel to another area. These waves left their DNA markers in the places they traveled and settled. These markers can thus be divided into one of a number of identifiable “haplogroups”, the migrations of which can be traced by examining what percentage of a population carries a particular DNA marker.


Y-DNA PROS:     Can help trace family surname

Can provide matches with other males that have the same marker, this might help solve “brick walls”, or place your father’s line at a specific place and time.

Can provide “deep” genealogical haplogroup information

CONS:                  Only traces direct paternal decent.

Can only be taken by males.


–          Familytree DNA offers a variety of Y-DNA tests that vary in price depending on how many markers are to be tested, and will provide member matches and surname work groups as well.

–          The Nation Geographic Genographic 2.0 DNA test is more expensive, but will trace the Y-DNA line as well as the Mt and autosomal tests. However, it is focused on providing haplogroup information more than more recent genealogical data.


This kind of DNA test examines mitochondrial DNA. This DNA is only inherited from your mother. Thus this test will only provide information about you direct maternal line – your Mother’s mother, and on back. Unlike the gender exclusive Y-DNA test, however, this test can be taken by both males and females. This test is useful in providing haplogroup information, but provides the maternal haplogroup rather than the paternal. Since mitochondrial DNA is always inherited directly from the mother’s line unchanged, population geneticists can trace concentrations of particular DNA markers around the globe and extrapolate migration patterns from that. Both Family Tree DNA and the Genographic project also trace Mt DNA.

Mt-DNA PROS: Can provide matches with other females that have the same marker.

Can provide “deep” genealogical haplogroup information

CONS:                  Only traces direct maternal decent.

Autosomal DNA tests

These are the types of DNA tests offered by popular genealogy sites like and 23andMe. The big advantage of this type of test, is that it traces both the father’s and the mother’s line. The drawback is that it is only accurate to a limited number of generations. You’ll get no haplogroup information here, but companies such as Ancestry do provide an “ethnicity estimate”. By comparing your DNA markers against a sample collection from various populations around the globe, a rough estimate can be made. They can, in effect, tell you “your DNA looks like its 20% Irish, 40% German, and 20% Russian” for example. Of course, this information can only be compared from comparatively recent generations, and is not the same as tracing one’s haplogroup back thousands of years. In addition, details about the sample population against which your DNA is being compared is generally proprietary, so we don’t know how many people were sampled, or from what exact area. Another big advantage of using companies like, is that your much more likely to find a match between your DNA and another user, since so many people use this popular site.

Autosomal tests:

PROS:    Traces both paternal and maternal lineage

More useful for more recent genealogy. Primarily 6 – 8 generations back.

Popular companies like and 23&Me can provide a large number users against which to compare your DNA.

In general, these tests tend to be a bit less expensive

CONS:   Lacks any “deep” genealogical component – does not provide haplogroup information

Usefulness is largely determined by how many other users of this service have similar DNA to yours – thus there is no way to know how useful the test will be before you’ve taken it.


Some accessible introductions to using DNA to trace populations available at your library:

Brian Sykes:        Seven Daughters of Eve

Saxons, Viking, and Celts

Spencer Wells:  Deep Ancestry

The Journey of Man

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