By Sara Whitford
As the Group Administrator for the East Carolina Roots DNA project through Family Tree DNA, I often receive questions about DNA testing. People want to know what kind of information they’ll be able learn from that little cheek swab, and it’s also important for me to tell them about the limitations of those tests so they’ll be clear on questions the tests cannot answer.
I might also be able to advise someone on the best way to find the answers they seek by letting them know how they can enlist parents and siblings, as well as close and distant cousins to be tested to provide further genetic information about their family’s genetic heritage.
Here are brief summaries in layman’s terms of the most common genealogical DNA tests available.
Y-DNA (Paternal) Testing
This type of testing looks only at the y-chromosome — the chromosome that is passed directly from father to son. Although this is one of the best genealogical DNA tests you could take in terms of reliability, there are still a couple of restrictions right off the bat:
- This test can only be taken by a man, because a woman does not possess the y-chromosome from her dad.
- This test will only reveal genetic connections on the direct paternal line — that means your father’s father’s father’s father’s father, and so on.
Now, that doesn’t exclude women from being able to find out about their paternal origins, but they’ll have to get someone else to take the test. According to the Y-DNA entry on Wikipedia, “Women who wish to determine their direct paternal DNA ancestry can ask their father, brother, paternal uncle, paternal grandfather, or a cousin who shares a common patrilineal ancestry (the same Y-DNA) to take a test for them.”
Of the three types of tests available for genealogical DNA testing, this is by far the most useful and the most reliable, and a family tree can often be filled out quite nicely if you search the internet for connections with others who’ve tested for some of your other ancestor’s lines. (For example, I’ve found quite a bit of information about the Y-DNA lines of several of my male ancestors from many generations back because they’ve had direct lineal descendants — my distant cousins — in recent years take Y-DNA tests.)
The reason these tests can be truly useful is that they reveal genetic information about recent common ancestors within the genealogical time frame and you can use a genealogy paper trail to make sense of the genetic data provided by the test.
An example in my own family is that my maternal grandfather is a Morris by birth, but there was an oral tradition going back generations that our earliest known Morris ancestor, Laban Morris (b. abt 1784), “wasn’t really a Morris, but was really a Ledbetter.” One cousin remembers his elderly great aunt telling him about the family secret decades ago, but warning him from pursuing it because of some sort of controversy that apparently accompanied the name change.
We wanted to put a rest to this family mystery, and find out if there was any truth to it or not, and so my grandfather had his Y-DNA tested, and then my cousin had his tested, and the results verified what we already knew (that my grandfather and his cousin were related), but also verified what we suspected, but didn’t know, by listing several Ledbetters as genetic matches to them both. We’ve since expanded the testing to other Morris cousins and other Ledbetters we’ve met through genealogical research, and are trying to pinpoint which of a couple of likely suspects may have been the progenitor of our Laban Ledbetter/Morris.
mtDNA (Maternal) Testing
Reliable? In ways, yes.
Useful? It can be, depending on what kind of information you’re seeking. You won’t get the same definitive results here that you would from a Y-DNA test, but it’s still interesting.
Here are examples of a couple of ways in which the mtDNA tests can be useful (possibly):
- You want to find out if your maternal great-great-grandmother really was an Indian princess. Will this test definitely tell you one way or another? Well, not the princess part, but as for the Indian part, if it comes back with one of the mtDNA haplogroups for American Indians, then yes. But if it comes back as some other haplogroup not belonging to an Indian group, that still doesn’t rule it out. If every other ancestor of that grandmother was Indian, but her mother’s mother’s mother’s mother’s mother was white, or black, or some other ethnicity, then her mtDNA test will not give any indication of her Indian roots.
- Your great-great-great-grandfather had three wives and you’re not sure which of them was the mom of your great-great-grandmother. A test like this could be useful if the direct lineal female descendants of his other known wives were living and were also tested, because then you could either rule in, or rule out, being descended from one of their ancestresses by whether or not your results match with theirs.
Beyond circumstances where you already have a paper trail and other possible or probable relatives with whom you could compare results, the mtDNA test results reflect both a time frame too far in the distant past, as well as a lineage with nothing as easily traceable as a surname (in most cases) from where you could determine how to fill out your family tree with the data.
If someone was interested in DNA testing in general — irrespective of any specific DNA project — of course I’d encourage them to get both their Y-DNA and mtDNA tests done. Perhaps refinements will be made to the mtDNA tests in the future that will improve the information that genealogists can harvest from the results.
Autosomal DNA Testing
These are the tests that promise to reveal your ‘deep ancestral origins’ or to ‘reveal your tribe.’ Sadly, it is a test that has misled many people into forking over big dollars.
One site boasts, “Find out where your ancestors came from, their ethnic background, and how they have scattered throughout the world today.” Another site goes so far as to claim to be able to break down your ethnic heritage into percentages, “Discover your estimated percentage of ancestry from four different population groups: European, Indigenous American, Sub-Saharan African, and East Asian.” (Funny story: Several members of my family had this test done several years ago and the results were all over the place. There is no logical explanation why there was no consistency whatsoever from such close family relations. )
According to the Wikipedia entry on Autosomal DNA testing, “These attempt to measure an individual’s mixed geographic heritage by identifying particular markers, called ancestry informative markers or AIM, that are associated with populations of specific geographical areas.”
The theory behind such tests is interesting, and I imagine they will get better with time, but there are some serious shortcomings that a test like this will never be able to surmount, such as dealing with the genetic remnants of many east coast Indian tribes (not to mention countless other indigenous people groups around the world).
In particular, how can you claim to have genetic samples from which you will make marker comparisons when there are no full-blooded members of many of those tribes from whom samples can be taken and included in the databases? For example, if the bulk of your Indian ancestry comes from coastal North Carolina and you are a direct lineal descendant on either your mother or father’s lines (not the other grandparents — just your direct maternal or paternal lines) from one of those tribes, then you might be able to get conclusive evidence from a Y-DNA or mtDNA test, but there are no samples from full-blooded citizens of Secota, so how could an autosomal DNA test know what markers to look for? To assume that an Indian from Pomeioc or Core Town would have the same genetic markers switched on as someone from Tohatchi on the Navajo reservation defies logic. They are genetically very different people groups.
The best these tests can do is make guesses based on a limited genetic sampling of living or recently living specimens from around the world.
DNA Projects
If you have DNA testing done, you’ll soon find out that there are countless DNA projects to which you can submit your DNA. Some can be very useful for fleshing out more information for your family tree, whereas other projects’ primary value might be vanity-based as they aim to recruit subjects tied to some historical theme.
If I were to recommend DNA projects for people to join, I’d probably point them first to surname projects (for Y-DNA tests), and then to regional projects for individuals whose ancestors came from specific areas. Regional projects can be particularly useful for finding out about the genetic heritage of other lines in your family tree for whom you might not have known living relatives eligible for testing. For instance, you might find some distant cousins who are the great-great-grandchildren of one of your great-great-grandparent’s siblings and where as you might not be able to be tested for that line because of a break in the gender lineage, others might have already had that line tested so you can find out information from their results.
If you really have a good grasp of how DNA testing works and what the results can and cannot reveal, then you might have fun browsing around various history-themed DNA projects, but to join a DNA project with the primary goal of linking yourself to some significant event in history is probably not the best investment unless you’re independently wealthy. DNA testing is not cheap. It starts at around $100 for the most basic test and goes on up to $400-$600+ for some of the FamilyFinder and complete genome variant tests.
For Your Privacy, Be Aware…
Before you join ANY DNA project, be sure you’re comfortable with your project administrator and whoever has access to your DNA results. Be sure there is a clear understanding between you and the administrators as to what are their purposes are for gathering data, as well as any plans they might have for using such data. FTDNA gives project administrators for DNA projects access to DNA testing profile information for the individuals in their DNA project. That may include other test results that are NOT part of the project, as well as any other projects to which their project members belong.
