A lack of regulatory oversight and limited comparable samples create opportunities for inaccurate or misleading genetic results.

With rare exceptions, our DNA is incredibly detailed and individual to each of us. As a result, you may believe that submitting your DNA to a variety of genetic testing services would result in identical results from each of them. However, this is not the case. In fact, how detailed your DNA is has a lot to do with the results being as varied as they usually are. But that’s just one factor.

A more important factor is that each of the genetic testing services create and utilize their own definitions for how to sort and label your results as there are no regulations and no oversight for these companies. The validity of the results is not ensured, and the standards vary quite a bit. In other words, despite it being a scientific venture, there is no open access to the information or peer reviews as is usually the case for scientific research. In fact, Dr. Simon Gravel, a population geneticist from McGill University, describes DNA testing as a “recreational scientific activity.”

Importance of Geography

One of the biggest misconceptions about DNA test kits is that they show you where your ancestors were from. The truth, according to Adam Rutherford, a British geneticist, is that “they’re telling you where on Earth your DNA is from today.” Of course, this is still useful information that gives you a tremendous insight into where your ancestors most likely lived, but it is not as accurate as expected by many as far as this aspect of their results go. In other words, if your DNA shows that you’re 30% Norwegian, that means that nearly a third of your genes match up with those currently in Norway, not necessarily those who were in that country hundreds or thousands of years ago.

Of course, it should be noted that, if you go back far enough, we all date to whoever the first human was, whether that was in Africa or elsewhere, so all geographical information is dependent on timing. If you and your family live in and are from Tennessee, perhaps your entire genealogical past dating 50 years is from that state. But if you go back 200 years, it might then include a few other states including or no longer including Tennessee and maybe a number of other countries. However, if you could reach thousands of years into the past, the situation likely gets either a lot more complicated or a lot simpler depending on a number of factors. The bottom line is that DNA testing is an inexact science as it relates to researching the geography of your family tree.

It’s also important to consider how many people are from certain geographic areas in the database of the genetic testing company that you use. For example, Debbie Kennett, a British genealogist, said that English users who send their DNA to American companies such as AncestryDNA and 23andMe will not be as likely to find results of value than if they send them to companies with more English users. Additionally, American companies will tend to have more information for DNA samples that have European genes than elsewhere since many American users have European ancestry. In other words, somebody with Syrian roots may not receive as useful information with these companies than those with European pasts.

Also, it can be difficult to find useful results with any of these companies if much of your ancestry is from a region where few users exist. This is generally the case for DNA that’s focused on regions outside of Europe as more people with European backgrounds have had their DNA tested with all of the companies than those from the world’s other regions. However, Kennett did add that DNA testing is pretty accurate in relation to finding out geographical connections with one or more continents. The issue comes when attempting to narrow the focus within those continents to smaller, more specialized geographic areas. This is complicated by the fact that different companies label regions within continents in varying ways.

The bottom line is that the size of the reference panel, the number of DNA samples that are already in the system and accessible by a company, has a great deal to do with how accurate the results will be. In other words, the more samples that your DNA are compared with, the more precise the results will be. The most important benefit related to this aspect of DNA testing is that, as more samples are added, your results will become more precise, so you’ll be able to continue learning more about your results as the years pass despite your DNA obviously never changing.

It should also be noted that the reference panel consists primarily of paying customers, which also skews how accurate the results are. In other words, if DNA tests were free and otherwise similarly accessible to everybody in the world and those people were equally interested in supplying their DNA to the testing companies, the results would be significantly more precise throughout the world, not just for those with European roots.

Twins Receive Varying Results

CBC recently reported on twins receiving “mystifying” results after they sent their DNA to five different companies. Twins have DNA that may not be 100% identical with each other, but the closeness nears 100%. As a result, most would expect the results that DNA testing companies provide them to be identical or at least extremely close to being identical. However, this was not the case when Charlsie and Carly Agro put AncestryDNA, 23andMe, FamilyTreeDNA, Living DNA and MyHeritage to the test. This despite Dr. Mark Gerstein, a computational biologist from Yale University, reviewing their DNA and saying that they’re “shockingly similar.” He added that the results that they received from those companies should have been identical.

One of the examples of these differences was 23andMe returning results that revealed that Carly’s “Broadly European” percentage was 13% while Charlsie’s was 3%. Also, Charlsie had 3% “French & German” ancestry while Carly had 0%. In addition, Carly’s results mentioned a specific link to Poland, but Charlsie’s results did not mention that country.

The company responded to CBC’s inquiry into why the results were different for the twins by saying that minor variations in the parts of the DNA that was analyzed led to the varying ancestry estimates. What occurs when the company analyzes DNA is that it looks at about 700,000 of a sample’s 3 billion parts, and, in this case, that resulted in 0.4% of the samples that were looked at being different from one twin to the other and the results then being slightly different.

What AncestryDNA and MyHeritage revealed was more similar than 23andMe did but not identical.

However, Living DNA showed significant differences. According to that company, Carly had ancestry in England, but Charlsie did not; hers in that region of Europe was limited to Ireland and Scotland. Also, one significant difference between the companies’ results was revealed by FamilyTreeDNA, which found 13-14% of both twins’ DNA being connected with the Middle East, well above the correlating percentages that was found by the other four companies.

Triplets Also Provided Different Results

Inside Edition also recently reported on people with nearly identical DNA sending samples to DNA testing companies and seeing how similar or different the results would be. In this case, those being studied were three sets of triplets and quadruplets. These included Erica McGraw and her sisters, Nicole and Jaclyn, Erin, Mandy and Melissa Maynard, an unnamed set of triplets from New Jersey and a set of quadruplets, Catherine, Christina, Janelle and Jodi Pyfrom. Interestingly, the quadruplets and the New Jersey-based triples received nearly identical results, but the same could not be said for the other two sets of triplets.

Erica McGraw and her sisters used 23andMe, and the Maynard sisters utilized FamilyTreeDNA, while the New Jersey-based triplets sent their samples to AncestryDNA. The main difference for the first set of triplets was the differences in their “French & German” ancestry with Erica at 22%, Jaclyn at 18% and Nicole at 11%. The primary difference for the second group was their British Isles ancestry with Melissa at 70%, Mandy at 66% and Erin at 59%. Also, Mandy showed as being 6% Scandinavian while Erin and Melissa were both at 0%.

How Much Syrian Ancestry?

Kristen V. Brown recently had her own questions about the trustworthiness of the DNA results that she received after some surprising details were revealed, information that she did not believe was accurate. In this case, the warning that DNA-testing companies provide of the revealed information possibly including identity-disrupting surprises ended up coming true. However, the author and her family still sensed that the surprise was not accurate. Regardless, what really troubled her was that, after taking four tests, she received “four very different answers about where my DNA comes from” in addition to the results that “contradicted family history I felt confident was fact.”

Specifically, her grandfather had initially believed that he was the son of two Mexicans. However, once he learned that he was adopted, he, at the age of 10, did some firsthand research by meeting his birth mother and discovered that his roots were Syrian, not Mexican. But what confused matters occurred when her aunt, his daughter, sent her DNA to AncestryDNA. It was expected that she’d be at least 50% Syrian since her father was believed to be a full-blooded Syrian. However, it showed up as well below that, 15% Caucasus, which AncestryDNA defines as including Syria, and 16% Middle East. Also, her aunt learned that she was 30% Italian-Greek. Additionally, her mother took a DNA test that showed similar results.

What likely resulted was the lack of Middle East-based samples skewing the numbers for that region. Until the number of samples from those with connections with that area of the world increase, this will likely remain the case for a period of time.

Some of the interesting information that Brown discovered was that her own AncestryDNA results showed her as having similar percentages connecting here with the Caucasus and the Middle East as her mother and aunt despite Brown expecting those to be roughly half as high as theirs. Conversely, she took a test with National Geographic that showed even stronger links with those regions. Also of note, AncestryDNA revealed her as having a 32% connection with Scandinavia, which made sense since her father is Norwegian, but 23andMe’s results only showed a 3% connection with that region. Also, GenCove revealed her having 8% DNA from the Indian subcontinent while 23andMe had her with a 0% connection with South Asia.

Different Companies Analyze Different Things

This doesn’t necessarily mean that results are more or less accurate from company to company, but it should be noted that all of the DNA-testing companies look at different things. Although they analyze SNPs, which is the part of the genome where differences between people as they relate to things like ancestry, appearance and disease likelihoods appear, they don’t analyze exactly the same areas. In fact, Joseph Pickrell, the CEO of GenCove, told Brown that he was “a little confused” by how different their results for her were from the ones that 23andMe had provided. He had expected some variability but not to the significant extent that ended up resulting.

It should also be noted that genetics is a probabilistic science. That means that, regardless of how accurate the information becomes, it will always only be a prediction. Nothing can be said for sure, both as it relates to your past as well as your future. In fact, some disagree that DNA is a trustworthy resource for determining how likely or unlikely the odds are that you’ll contract a certain type of disease while others state that only experts are able to analyze genetic results to a high enough certainty for that information to be truly reliable and useful. Regardless, your lifestyle choices will generally play a greater role.

A useful resource for comparing what the different DNA-testing companies analyze, which services they offer and other factors has been compiled by the International Society of Genetic Genealogy Wiki. If you’re deciding to use one or more of these services, this is an invaluable resource to look over before making your decision. Just ensure that, despite what many AncestryDNA ads may tell you, your results will not define your identity; your genes do not determine your culture. They play a role, of course, but they are not the be-all and end-all.

DNA testing and the analyzing of those results is a fairly new development, and it will continue to evolve as time passes. In fact, the first human DNA sequence to be delivered occurred in 2003, thanks to the Human Genome Project. Fortunately, that development resulted in DNA being able to be read and analyzed and ever-increasing speeds and at decreasing costs. But it will take time for that information to be as accurate as would be preferred, and, as long as no oversight exists for these companies, it will be difficult to completely understand what the information being provided truly means and how accurate it is.