How Accurate Are DNA Kits and Which Ones Can You Trust?

Top10.com StaffByTop10.com StaffMay. 22, 2019
DNA test kits are accurate
You have likely read about them, have a friend or family member that has tried one, or been wanting to give one a try yourself. DNA testing kits are all the rage nowadays, and are used by people of various backgrounds to learn about themselves and their family’s history.

We’ll look at DNA kits and their accuracy, as well as the basics of DNA and how it can be harnessed to learn about your past, present, and in some cases, your future. 

What Does Accuracy Really Mean?

Let’s first identify what we mean by accuracy. The mainstream home DNA kits claim to read your DNA and either match you to other people in the database as family, build a family tree for you, or both. So when we question if they’re accurate, what we really mean is how well can these tests identify if you’re related to other people in the database.

The most straightforward answer is, pretty well. If you’re white caucasian from European descent the test might reveal more information about you than someone with different heritage, but that’s only because the databases of these major companies match that heritage.

Another factor to keep in mind is that the companies utilize a statistical approach to ancestry, which means that they only tell you how probable your ancestry is. When viewing your results you’ll notice that every relationship has a percentage next to it, which is the likelihood of accuracy.

There are some incredible stories of DNA kits providing people with answers to their questions, and assuring them that the stories they’ve heard from their grandparents are in fact true.

One example of how accurate DNA kis are is with the story of 3 identical triplets who used 3 different DNA kits to test each one’s accuracy. The story was featured on The TODAY Show, and the prediction was that the tests would provide answers, but answers far less detailed than the triplets received. The 3 sisters were filmed sending in saliva and cheek swab samples to 3 popular companies – 23andMe , MyHeritageDNA , and AncestryDNA . Much to their surprise, the results from all 3 companies were identical. All kits gave the same results, predicting the same ancestry for each individual sister. Additionally, each test said that there was a 100% relationship match to the other 2 sisters. This is just 1 of many stories that show the extreme accuracy of DNA tests.

DNA testing works by analyzing your specific DNA and comparing it to other samples. The aim is to find similarities or differences in the genetic markers, which can then provide answers. A shortcoming of the science is that the analysis of the DNA is done by comparing it to other samples in a database. This means that the tests get more accurate as the size of the company’s database increases. For this reason, it’s best to choose a company with a large database if you’re looking to find answers regarding your ethnicity, ancestry, and where your family comes from.

What Can—and Can’t—be Determined by DNA Tests 

One thing to look at first and foremost are the limitations of these tests. When it comes to DNA tests for ancestry, they can’t tell you precisely where your ancestors lived because the test can’t directly compare your DNA to that of those exact ancestors, and because it’s very difficult to tell the difference between populations living in 2 nearby areas. 

Also, as was mentioned above, certain populations—mainly people from European backgrounds—are more represented in the testing data, and are more likely to receive more detailed results for their tests. And unless you use a test that checks only your matrilineal or patrilineal bloodline, you won’t be able to tell which percentages of your ethnicity came from which parent. 

You also shouldn’t count on using a DNA test to establish Native American ethnicity, as most Indian tribes have their own criteria and DNA tests also don’t provide specific enough details about Native American ethnicity, such as which specific tribe or nation is reflected in your DNA. 

And while your DNA test should be able to find measurable results heading back 6 or 7 generations or so, once you start going back further than that, the ability to get solid results will thin. 

Your DNA test can determine if you have other relatives that share your DNA and have submitted their test results online. This “relative matching” looks for people you share a genetic connection with, though typically you’ll find that these are more distant relatives, such as 4th or 5th cousins, or 2nd or 3rd cousins removed. If these people have submitted their results and the company you use has access to these results, you can match with them and gain crucial insight that can help you build a family tree with details you never had before. 

Genetic testing looks at probability, so while your DNA sample may indicate that you have a greater likelihood to contract a certain genetic disease, it by no means qualifies as a diagnosis. 

Maybe this goes without saying, but while a DNA test can assess your ethnic breakdown by percentage, find your probabilities of genetic illnesses, and help you find long lost relatives online, it can’t tell you who you are or what your identity is. If for instance, you have lived your whole life as a certain race and in a certain culture and environment, finding out say, that you’re actually 18% sub-Saharan African or conversely, 15% Norwegian, does not mean you need to rethink who you are. 

Life just isn’t that simple. 

Can DNA Testing Make Mistakes? 

DNA tests typically don't look at your entire genome, rather, they look at specific parts of your DNA that are of interest. As a result they may miss specific variants that are picked up by more thorough tests. The size of one company's DNA sample database can also have an effect on how detailed your results will be and there is also the issue of false positives—one analysis found that in direct-to-consumer DNA tests, 40% of the variants associated with specific diseases turned out to be false positives

There is also simply the issue of interpretation. Genetic science is largely an issue of probability. For instance, you look at a group of people who all have a specific disease, and then look in their DNA for places that are similar among the test population, as opposed to in the general population. Analysts try to assess linkage and if you share genetic markers of other populations that have certain traits. It isn’t that there is a specific gene “for” anything, it’s more an issue of probability and analysis. 

In addition, there can be incidents in which a lab mishandles results, which has the potential to be very shocking and disruptive, especially in the case of paternity tests. 

Looking beyond the world of home DNA kits, we can see in wider society a number of problematic issues surrounding DNA testing. In the criminal justice system, DNA evidence is seen as so scientifically solid and unsassaibleable that it has been used to free people wrongfully convicted of crimes, and also imprison a growing number of people. As DNA analysis technology has become more sensitive and sophisticated, so has the likelihood of false positives, including that someone’s DNA will be present on someone just because they touched the same object or because different pieces of evidence jostled together in police custody. 

DNA samples can also be handled poorly or contaminated, and can become a problematic part of an investigation, such as in the infamous murder trial of American student Amanda Knox in Italy. 

At some level, the problem isn’t with the DNA sample itself, rather, the person handling it. This can have grave consequences. For instance, in October 2018, a Texas state commission ruled that a Texas Department of Public Safety crime lab chemist had failed to thoroughly analyze key DNA evidence in the case and in May 2005, a Virginia state audit found that one of the premier crime labs in the United States botched DNA testing in the case of a man who spent 17 years in prison before being exonerated.  

Basics of DNA Testing and What Each Reveals

There are 3 main types of DNA tests available – autosomal (atDNA), mitochondrial (mtDNA), and Y-chromosomal (Y-DNA) – each one useful for different purposes.

atDNA

An atDNA test analyzes 22 out of the total 23 pairs of chromosomes. These chromosomes are inherited equally from both parents, which means they can be used by both males and females. A person gets half of their markers from each parent, a quarter from each grandparent, an eighth from each great grandparent, and so on. Because of this, an autosomal DNA test is the best kind of test for finding a range of relatives. It’s important to keep in mind that results get less reliable the further back you go because autosomal DNA changes every generation.

mtDNA

An mtDNA test checks mitochondrion, a component of the human cell. Mitochondrial DNA is passed down from mother to child, which makes it possible to trace back a direct maternal ancestor. A mitochondrial test gives incredibly precise results about ancestors and distant cousins, but only from your mother’s side. It can also help you learn about certain regions you may come from, your ethnicity, or family group.

Y-DNA

Y-DNA tests examine genetic information from the Y chromosome only which are only found in males. They can therefore only be taken by males and only provide paternal information. Similar to the mtDNA test, these are good for tracing previous generations.

What DNA Tests Can Reveal

After taking a DNA test, you will be able to view your results—either online, in print, or both—which breakdown your ethnicity by outlining the regions you likely come from. For example, a possible ethnicity estimate could be England with 41%, Ireland with 28%, Denmark with 21%, and Sweden with 10%. This ethnicity estimate can also help you discover what religion your ancestors practiced.

Many DNA testing kits also provide ancestral reports, which determine how closely related you are to someone else. This can help you learn about your parents or grandparents if you’re adopted, and even help you discover long lost relatives you never knew existed. Many companies also offer family tree building software that fit your family’s puzzle pieces together to create one clear picture. A leader in the DNA testing space, MyHeritage, has one of the largest international networks of family records and family trees – 8.8 billion, and growing.

There are also paternity-specific tests that can confirm if someone is indeed the father of a child—some that can even be performed prenatally. Additionally, certain kits like Vitagene can use your DNA to tell you about your health. This can warn about genetic diseases that may run in your family and life changes you should implement that may help to ward off the disease. The company is backed by physicians, experts, and universities, and its DNA results include a personalized fitness plan for your specific level of health. It also tells you the vitamins or minerals your body is lacking, and which you should be taking more of. The test is also good for people who have tried diet after diet but still can’t seem to find the one that gets them the results they want. Because Vitagene uses your DNA and cell data, all the information is specific to you.

How to Choose a Reputable Company

With so many DNA testing companies out there, it’s important to choose a reputable one with positive reviews. Aside from MyHeritage and Vitagene, there are top companies like LivingDNA , 23andMe, and Ancestry.

LivingDNA is best known for its biogeographical ancestry results and its emphasis placed on security and privacy. This is desirable, as taking a DNA kit means your information will be seen and examined by others. Other services like 23andMe and Ancestry are known for their millions of customers and accurate test results. 23andMe provides over 75 reports on your health, traits and ancestry, and can help you discover where your ancestors originated from over 150 different regions. And with over 17 billion searchable records and 2 million new records added every day, Ancestry is a top choice.

With so many other users in the databases, these companies are getting better and better at building families and identifying who we’re related to.

The Real You is Waiting to Be Discovered

Although home DNA test kits are not 100% infallible, they are amazingly accurate in helping people find relatives and learn about their ancestry—particularly considering their price and convenience. It’s important to know exactly what a DNA test can—and can’t tell you before taking one. However, if you go into the test with the right mindset and information, it can be an eye-opening and rewarding experience.

Top10.com StaffByTop10.com StaffJun. 18, 2019
Our editorial staff is comprised of writers who are passionate about the world of genetic testing. We specialize in simplifying the process of choosing the right DNA testing kit for your needs.