The Reliability and the Ethics of DNA Testing for Genealogy (part 1)
DNA testing has emerged as a powerful tool for genealogists, both professional and amateur alike. The results of an Ancestral DNA test can help you to confirm connections and discover new branches of your family tree. With the accessibility of DNA heritage tests, like AncestryDNA, 23andMe, and Family Tree DNA, even the most novice Family Historian can use these test results to open doors that were thought to be lost and discover new family members you didn’t even know existed.
But, like all things, there are two sides to the Ancestral DNA test coin. With the proliferation of testing companies, questions about the accuracy of these tests have become increasingly important. So, what is the reliability of DNA testing for genealogy? Let’s discuss which tests I’ve used and which ones I like. Then, in Thursday’s post, I’ll explore ethical considerations related to this fascinating field.
How DNA Testing Works
Leading companies like AncestryDNA, 23andMe, and FamilyTreeDNA employ sophisticated techniques to analyze specific markers in your genetic code. By comparing these markers with those of other testers, they can pinpoint shared DNA segments. Through this DNA mapping, they are able to tell from the degree of shared DNA indicates the closeness of the relationship between individuals. One individual has about 6,800 cM — or centimorgans. According to the National Human Genome Research Institute, a centimorgan (cM) is the unit of measure for the frequency of genetic recombination. These centimorgans help to identify possible cousins, confirm ancestral ethnicities, and even uncover unknown biological parents or siblings.
Factors Affecting Accuracy
While no test can claim 100% accuracy, several factors influence the reliability of DNA testing:
1. Sample Size
The size of a company’s DNA database plays a crucial role in finding genetic relatives. AncestryDNA, with over 18 million tested individuals, offers a higher likelihood of discovering connections. It’s simple, the more people tested = the better the chances of finding DNA relatives. It also increases the accuracy of your ancestral ethnicities.
2. Marker Testing
Tests that examine more genetic markers provide more data for precise relationship predictions. For instance, 23andMe tests for over 600,000 genetic markers, while AncestryDNA tests over 700,000. The more markers tested, the better the accuracy.
3. Pure Family Trees
Endogamous populations, or people who marry within their own tribe or group, will offer minimal genetic mixing. Endogamy will yield more definitive results. However, distinguishing some ethnic groups accurately can be challenging due to a limited gene pool.
CHOOSING A DNA COMPANY
For genealogical purposes, AncestryDNA and 23andMe are often recommended due to several reasons:
- Large Databases: These companies have the largest sample databases, increasing your chances of finding relatives.
- Frequency of Updates: Both regularly update their databases and algorithms to improve accuracy.
Both AncestryDNA and 23andMe offer a way to see who your DNA Relatives are, sorting them by the closest cM matches and even letting you see what DNA relatives you share with the match. But one big difference is that AncestryDNA is linked to massive Genealogy Databases that allow you to cross-reference your DNA Matches, with the paper trail more commonly associated with Genealogy.
Which brings me to:
- Advanced Tools: Both companies offer sophisticated tools for analyzing and comparing results. One thing I love about 23andMe is they provide my maternal haplogroup without additional testing, Ancestry does not do this. And, if I were male, 23andMe would supply both Maternal and Paternal Haplogroups. Once again, this is not available on AncstryDNA.
- Integration: Integration with genealogical records like the databases compiled at Ancestry.com simplifies the research process. Clearly, AncestryDNA is the winner in this category. While 23andMe has a “Family Tree” selection, Ancestry is much easier to use when building your Family Tree and easier to navigate. And, as I mentioned before, with Ancestry, you have access to millions of documents that will help verify and show proof of your family connections.
- Detailed Insights: Both companies provide detailed ethnic breakdowns and historical context.
While these companies employ rigorous scientific methods, cross-referencing results with the traditional paper trail remains vital for accuracy. As DNA databases expand and scientific understanding evolves, DNA testing will continue to enhance its precision in tracing family histories.
But if all of this is true, then why did I grow up told I’m half Italian, but when I tested, I only have 23% Italian and a LOT of Greek in my DNA results?
Whenever you start researching your family history, it is vital to learn the history of the region you are working in. In my case, that would be the Mediterranean. Both Italy and Greece are closely located to each other. Knowing and understanding the basic migration patterns of this area has helped me better understand that while the paper trail of my family history says, “YOU ARE ITALIAN,” the DNA results will show those Italian ancestors moved around. Or maybe it was my Greek Ancestors who decided to move around a lot in Italy.
Another thing to keep in mind is that documents can be wrong, and people have been known to lie. For my DNA results, the migration patterns of the Mediterranean provided the answer I needed, but it is also important to accept that documents are not always correct.
This is why it is important to record all of your research and to find multiple documents to prove the correct family lineage. And then, there are the hidden stories in our families that DNA reveals. As the availability of DNA test increase, it is more and more common for people to find those hidden truths when they take a DNA test.
I have used both 23andMe and Ancestry DNA in that order. First, I chose 23andMe. I initially leaned towards this company because of their health results on top of the DNA and Ethnic reports. Basically, 23andMe is where I dipped my toe into genetic genealogy without realizing the obsession I was starting. I enjoyed 23andMe, and still do, but when I wanted to use these results to help expand my family tree — I found it confusing.
This led to my AncestryDNA test. When I sent away for the results, I already had a well-established Ancestry Family Tree. By taking their test, I was able to attach it to my ever-growing Tree, and by attaching AncestryDNA to my Family Tree, I found answers about a family branch left hidden for generations.
The longer I was with both companies, and the more I began to understand the use of “DNA Cousins,” the more I wanted to know about other DNA companies. This brings me to Family Tree DNA (or FTDNA). Unlike 23andMe and AncestryDNA — FTDNA allows you a *free* upload to their site.
What does that mean?
When you pick 23andMe and AncestryDNA, the only way to obtain results is by purchasing a DNA kit from their company. With FTDNA and some other sites, you can download your *raw DNA* from 23andMe and AncestryDNA and then upload it to the new site for free. No DNA Kit purchase is necessary. By doing this, you will learn a different take on your ethnic results AND increase your DNA Cousins pool. Other sites that also have a free upload policy are: GEDMATCH, MyHeritage, and LivingDNA.
There are more of these sites out there, but the ones listed I have personally used.
I’ve found expanding my DNA Cousins pool helpful. In the case of the hidden family branch, by using DNA testing, I went from knowing nothing to building a small tree that includes five of my second cousins (3x removed).
Due to DNA results— I have narrowed down the area where my family came from and learned the names of some ancestors. By having these results, I was able to transition over to traditional genealogy resources and able to build out the branches of our forgotten family tree.
The reliability of these DNA tests led me to answers I never would have found from the little information I had access to. They transformed the history of my family and exposed a group of resilient people who were lost in time.
For me, the use of ancestral DNA tests has been exciting, but the use of DNA to expand my family tree is only one side of the coin.
DNA is the biological blueprint of who we are on a molecular level. So, when we give a copy of that blueprint to all the DNA companies I mentioned, what does that truly mean?
DNA testing for genealogy raises important concerns about privacy, re-identification, and pre-existing conditions. In my next post, coming this Thursday, I will talk more about the ethics of DNA, expand on why DNA results differ from company to company, and discuss how they can affect other areas of your life.
Until then, Happy record hunting!
[Disclaimer: I am not a genetic genealogist, only a genetic genealogist enthusiast. If you are uncertain about taking a DNA test for genealogy purposes, please make sure to conduct deeper research on the pros and cons of DNA testing and reach out to specific companies who conduct these tests to be sure before sending off your sample.]
(Check out last week’s post: Ancestral Vacations: Connecting with Family History Through Travel. Follow my profile for alerts!)
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Aryn is a genealogist who researches family trees, a lover of local cemeteries, and a social history enthusiast. She helps people discover their family roots and heritage through researching their family history.