This article was scientifically reviewed by YourDNA
We take the information we share seriously. Review our Editorial Policy Here.
A list of references is also included at the bottom of this article.
As home DNA test kits become increasingly popular, more people are swabbing their cheeks or mailing off tubes of saliva to find out more about themselves, their family, and their genetics.
What's in this Guide?
- How DNA Tests Work
- How Accurate Are Today’s DNA Test?
- Can DNA Tests Be Wrong?
- DNA Test Accuracy Statistics
- DNA Tests For Genealogy
- Can DNA Tests Find Your Family Tree?
- DNA Tests For Cancer Risk
- DNA Tests For Pregnant Women
- Can DNA Tests Prove Infidelity?
- How Can DNA Tests Tell Your Ethnicity?
- How To Interpret DNA Test Results
- Finding A Genetic Counselor To Help You
- Popular Brands of DNA Tests
- Which DNA Test is Best?
Disclaimer: Before You Read
It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.
Genetics is a quickly changing topic. Read More...
But, as this newer technology is now more easily accessible for everyone, there’s a huge flood on the DNA test kit market.
Like any new science product, there are a lot of questions about how DNA tests work, how accurate they are, and whether the results you receive are truly understandable. Here’s what you should know about DNA tests.
How DNA Tests Work
If you choose to use an at-home DNA test kit, it seems pretty straightforward:
You receive the kit, follow the instructions for collecting a DNA sample, register the kit and mail it back, and then wait several weeks for results. While that seems simple, it still leaves you wondering what happens after you submit your DNA sample.
How does the laboratory process and analyze it? How accurate is it? And what are you going to learn about yourself?
For starters, it all depends on what kind of DNA test you’ll be using. For most at-home DNA test kits, you’ll send in a cheek swab or small vial of saliva.
These are normally collected by you rubbing a provided, sterile cotton swab on the inside of your cheek, picking up cells that contain your DNA, or in the case of saliva, by you spitting in a provided sterile tube.
Blood or hair samples can also be used to extract DNA — but in most cases, those kinds of samples are often only taken in less-than-usual circumstances, such as if your doctor requests a DNA test to evaluate your genetic makeup, if you need to have a paternity test done, or if you’re a suspect in a criminal investigation.
If you’re choosing to use an at-home DNA test kit, it’s more likely that you’ll be submitting a cheek swab or saliva sample, so don’t worry about having to pluck a hair or prick a finger to find out more about your genetic traits.
After mailing off your sample to the DNA testing company’s laboratory, the analysis work gets started. Computers are used to evaluate and digitize your DNA sample — presenting lab scientists with a string of four randomly repeating letters (C, G, A and T) that make your individual DNA chain.
What’s important to know about DNA is that these labels (called nucleobases) are used for interpretation. Scientists, using state of the art computer technology, can pick out patterns and strings of letters that are attributed to specific traits, such as whether you have curly hair, what your ethnic background may be, and if you are potentially a carrier of certain genetically inheritable diseases.
What’s important to know about how DNA tests work is that each genetic testing company’s laboratory uses different algorithms based off decades of genetic testing research to draw conclusions about your DNA.
This is especially apparent when it comes to determining family lineage or ethnicity, and often the results are dependent upon how many other samples are available in their database for comparison.
Furthermore, DNA testing companies do not collaborate on their databases or algorithms, which means that it’s hard to know exactly what kind of results you may receive, and why the results can vary — sometimes drastically — from test to test, at least when it comes to tests for information such as family tree matching and ethnicity.
So, what are researchers looking at when you send in your DNA for analysis? For starters, when it comes to tracing genetics, scientists will be explore your chromosomes.
Humans have 23 pairs of chromosomes, with one set being used to define sex (male or female) and the remaining 22 pairs used to determine a variety of factors related to what makes you you, such as health, height, and other inherited features. When evaluating these chromosomes, scientists will be looking at three different kinds of DNA that they impact:
- Y-DNA: If you’re male, researchers will examine this subsection of your DNA, held in the one pair of sex-related chromosomes. Men pass on the Y chromosome to their sons, and this information, called Y-DNA, can be used to track paternal ancestry — that is, genetics passed through your father’s line. If you’re a woman, you won’t have any Y-DNA, and that has lead many DNA test-takers to question who in their family (such as a father, brother, uncle, or son) should be tested when it comes to determining ethnicity or family history.
- Mitochondrial DNA (mtDNA): Unlike Y-DNA, everyone has mitochondrial DNA, because it’s passed from mothers to all of their children in the form of an X chromosome — if you think back to high school science class, you’ll remember that men have an XY chromosome pair, while women have XX chromosome markers for sex. Women pass along the necessary X to children, and there are some DNA tests that specifically trace maternal DNA. Though, confusingly, new research suggests it may be possible for men to actually pass along mitochondrial DNA as well.
- Autosomal DNA: After observing the clues your sex-related chromosomes give researchers (the mitochondrial DNA and/or Y-DNA), they’ll also start observing the remaining chromosomes that help make you are who you are. These remaining 22 pair of chromosomes — called autosomes — contribute your autosomal DNA. This information can provide tons of data about your genetic health, how your body responds to medications and medical care, the impact of nutrition on your specific genes, conditions you may be a carrier of, your personal risk factor for certain diseases and so much more.
Computer algorithms are able to look at these portions of DNA, and compare them to other DNA in the company’s database, looking for matches on particular traits, such as ethnicity.
When the DNA doesn’t match a group — for example, the group for Scottish ethnicity — it moves on to other groups to continue looking for a match.
Some at-home DNA test kit providers are able to compare your DNA with more than 40 different ethnic groups, so it’s important that if you’re looking to use DNA as way to learn about your family history that you go with a company that has an extensive DNA database.
How Accurate Are Today’s DNA Test?
Now that you understand the basics of how DNA tests work, you may be wondering how accurate they are.
While many tests report to have a high level of accuracy, it truly depends on what kind of information you are looking to receive.
According to some geneticists, these at-home DNA tests can be spot on in some areas, but can often give false representations of family origin and history.
When it comes to testing for factors that are specific to you because of your autosomal DNA, such as whether you are likely a carrier of a certain disease or illness-causing gene, such as Huntington’s disease or Alzheimer’s disease, DNA tests can be very accurate.
In fact, some genetic testing kits, such as 23andMe have received FDA-approval for testing on risk for some diseases, such as Parkinson’s disease.
Accuracy at this level of DNA testing is possible because researchers understand that particular gene mutations can lead to certain diseases, and they can observe specific portions of your genes to determine if you have that mutation and risk.
When it comes to DNA tests that report your “percentages” of different ethnicities, the waters of accuracy are a bit more murky than the commercials may present. Some geneticists believe that the reported, specific numbers you receive — for example, being told that you are 50.3 percent German — have a large possibility of being wrong.
That’s because tests rely on comparing your data to other DNA that a computer defines as different ethnic groups, and looks for a match.
The large the testing company’s database, the higher probability your test will be more accurate, but you should know that no test can definitely tell you how Irish, how German, or how African you are.
Can DNA Tests Be Wrong?
With the new and quickly innovating world of at-home DNA test kits, it is possible for DNA tests to be wrong — though it is difficult to tell unless you take several tests and compare the results to one another.
When it comes to identifying your risk for genetic illness, or to determine if you are a possible carrier of a hereditary disease, the likelihood of your test being wrong is quite low.
But, when it comes to tracing your family’s ancestral lineage through a DNA test, there’s a good chance that that data isn’t spot on, or could be wrong.
Many people have asked, “Is my DNA test inaccurate?” because of results that do not match up with their family’s identity, culture, or stories.
One of the largest reasons for this is because modern humans are using technology to trace their ancestors, but the technology often doesn’t account for how much humans moved around.
The data used to determine where your family is from also is comparing modern DNA, not the DNA of our relatives. This can be confusing, and Adam Rutherford, a British geneticist, says explains it this way:
“They’re not telling you where your DNA comes from in the past,” he told Gismodo.com. “They’re telling you where on Earth your DNA is from today.”
Regardless of how you identify or what your family history is, it is important to know that everyone has some kind of ancient African DNA. Seeing this DNA present in returned results is often one reason why people as if their DNA test results are wrong.
In reality, it is accurate — that’s because scientists believe all humans have descended from a group of ancient humans that originated from that region.
DNA Test Accuracy Statistics
One way of evaluating which at-home DNA test kit you should purchase or use would be to go with the test that has the most accuracy, though accuracy statistics aren’t widely available or clear.
In fact, because each company uses different genetic markers and databases to determine your ethnicity and other, and because the databases and algorithms used for comparison are proprietary and protected, there is no clear way to determine how accurate a test is, simply because they are not easily comparable.
Many geneticists warn against at-home DNA test kits that report to give extremely high levels of accuracy, simply because there is no way to evaluate these company’s claims.
When it comes to genetic testing done for paternity or health issues, which is often done using blood or hair samples and provided by a doctor’s office, you can expect these results to be highly accurate.
In cases of paternity, tests can determine with up to 99.9 percent accuracy 1 whether someone is your father or mother, though it may be less with siblings.
That’s because on average, full siblings share about 50 percent DNA, while half-siblings often only share an average of 25 percent of DNA.
DNA Tests For Genealogy
There is a booming market for DNA tests used for genealogy. These tests rely on all three kinds of genetic testing:
Autosomal DNA, Y-DNA, and mitochondrial DNA 2 (mtDNA) — to help trace your family history. In fact, some tests are specifically marketed towards the kind of DNA that is most useful for you (based on sex).
The Most Accurate DNA Test For Ancestry
Unfortunately, there’s no one “most accurate” DNA test for determining your ancestry. Many people seeking to learn more about their family’s histories seek out tests from 23andMe or AncestryDNA, two of the most popular home DNA test kit providers.
Because so many people use these DNA databases, it is possible for these two genetics testing companies to have a higher level of accuracy in comparison to a smaller company with a smaller database.
Problems With Ancestry DNA Tests
Because ancestry DNA test companies don’t collaborate with one another, there are bound to be problems with analyzing your DNA.
One of the largest problems is that comparing DNA of modern humans can only tell you who you share similar DNA with — and that person is someone who is currently alive and has also submitted their DNA.
This has led many families to feel that their ancestor’s histories or stories weren’t accurate, simply because the DNA analysis they received didn’t match up.
Researchers, writers, and journalists across the internet have published stories about how DNA tests can create confusion for families, specifically for these reasons.
While these at-home DNA tests can make it easy for you to potentially link up and find unknown family members, they can also be confusing and not necessarily give clues to your family’s background and history.
Can DNA Tests Find Your Family Tree?
Most people don’t know their families beyond themselves, their parents, and their grandparents.
So, the modern use of DNA kits has given a huge rise to people being able to find out more about their family trees.
DNA test providers such as AncestryDNA and MyHeritage DNA combine both your genetic results with maps, graphs, and historical records and documents to help you compile your family tree.
Other companies, such as 23andMe, can also provide this information, though often don’t have the historical records databases that can help you along the way.
DNA Tests For Cancer Risk
One modern benefit of at-home DNA test kits is that they can clue you into your risk for cancer.
According to the American Cancer Society, most types of cancer are not caused by gene mutations that have been passed down from parent to child.
But, about 5 to 10 percent of cancers are, and people in high-risk families (where cancer has appeared many times, often called a cancer cluster) can consider the use of DNA tests to determine if they have heightened risks.
23andMe is the most popular DNA testing company that offers cancer risk analysis, specifically for BRCA genes that are known for their link to breast cancer.
If you feel that you have a heightened risk, submitting a DNA sample can help you and your doctor determine future courses of treatment to help reduce your cancer risk.
DNA Tests For Pregnant Women
One of the most-hated parts of pregnancy is waiting up to 20 weeks before finding out if the baby you’re carrying is a boy or a girl.
One company, called Sneak Peek, offers DNA testing that alleges to be 99 percent accurate and gives results as early as nine weeks of pregnancy.
While these tests haven’t been evaluated for accuracy, it’s really the only kind of test specifically marketed to pregnant women beyond tests that determine your chances of being a carrier of certain hereditary disease.
And because at-home DNA test kits rely on cheek swab or saliva, you should know that these tests won’t work for paternity, or won’t be able to tell you your baby’s genetic makeup.
Can DNA Tests Prove Infidelity?
Depending on the circumstance, it may be possible that a DNA test could prove that a spouse has been unfaithful — but in most cases, that’s only if a child is suspected to have a different father.
A DNA test comparing the child and parent can be used to determine if they are related, and the results of such can then be used in court if necessary. In most cases, though, if DNA is needed to support a divorce of child custody case 3, the court will require a laboratory test to ensure that results are accurate, timely, and not tampered with.
How Can DNA Tests Tell Your Ethnicity?
DNA tests can be used to give you an idea of your ethnic background, but there’s no guarantee of their accuracy.
That’s because each DNA testing company uses different genetic markers to determine characteristics about each ethnic group, and then tries to compare your DNA to determine if you fit those characteristics.
It’s very possible for you to be a member of that ethnic group and for test results to say otherwise.
It’s also possible for those test results to vary by testing company.
DNA Tests For Native American Ancestry
When it comes to determining if you are a member of a Native American tribe, genetic testing 4 can be somewhat controversial.
That’s because of the history of lost native communities, and how many communities have been disrupted and struggle to maintain their identities within the United States.
Some tribes have considered using DNA testing for tribal enrollment, though because these tests have no regulation regarding accuracy, they may not be accurate. For this reason, other forms of testing, such as DNA fingerprinting, can be a good alternative.
DNA Tests For Jewish Ancestry
Many researchers who want to explore their Jewish roots through DNA testing have found difficulty with at-home DNA test kits.
According to Ancestry, that’s because many Jewish communities have a practice of marrying only within the community, which can lead to confusing results with many cousin matches, often leading test-takers to wonder, “Is my DNA test inaccurate?
In addition, genetics results often show ethnic matches from widely across Europe, but that doesn’t mean these DNA test results are wrong. While it may take more digging and the help of a Jewish genetic counselor or researcher, it is still possible to use DNA tests to explore your Jewish ancestry.
How To Interpret DNA Test Results
When it comes to interpreting your DNA test results, most companies will send you a slightly detailed analysis about what you’re seeing.
If you are looking specifically for family ancestry information, most test companies will walk you through maps of where your genetic markers are geographically related to, while also showing possible migration routes for your family.
If you choose to opt in, these DNA results will also help pair you with potential family members by showing you how related you are, and what traits you share.
When it comes to health-related DNA test results, your selected laboratory will explain whether or not you have certain genetic markers for certain diseases or health issues, making it easy to understand whether or not you carry some risk, or may pass along a health risk to a child.
Interpreting DNA test results can be confusing, so it’s not a bad idea to consult with a genetic counselor if you do not understand the analysis you’ve received.
Finding A Genetic Counselor To Help You
If you are looking for a professional who can guide you through the genetics analysis of DNA testing, it’s best to start in your own community.
Genetic counselors are a great resource, especially if you are specifically undergoing a DNA test to determine if you are a carrier of a gene mutation that can cause you or a child a health risk. Some of the best ways to find a genetic counselor include:
- Getting a referral from a doctor or current health provider
- Speaking with your insurance company to see if any genetic counselors near you are covered by your insurance
- Research genetic counselors at research hospitals or universities in your area to see if they are available to help you
- Getting a referral from a genetics organization, such as the National Society of Genetic Counselors 5
Popular Brands of DNA Tests
As at-home DNA test kits become more and more popular, more and more brands have hit the market. The most popular brands of DNA tests include:
- AncestryDNA: Uses DNA testing to determine your family history
- 23andMe: Does family history DNA testing, as well as health testing for a variety of potential health concerns
- Living DNA: Determines family history, and is able to trace both the maternal and paternal line for a lower cost
- MyHeritage DNA: Explores your family history and ethnicity, and is a cost-efficient option
- FamilyTree DNA: Another family history tracing DNA company, and is considered a better option for individuals who have higher budgets
- National Geographic Geno 2.0: Considered a more expensive option, Geno 2.0 is less detailed than many other popular DNA test kits and explores how much DNA you share with Neanderthals (don’t worry, we all have Neanderthal DNA).
Which DNA Test is Best?
It is difficult to determine exactly which DNA test is best, and that’s because there are many different factors that go into determine which DNA test works best for you and the results you are looking for.
If you’re most interested in family tree research, Forbes recommends that AncestryDNA is the best DNA test kit to go with because of its resources and large DNA database.
On the other hand, many reviewers who utilize DNA tests for health research believe that 23andMe is the better test to use, simply because it is more focused on health research.
When it comes to determining which DNA test is best for your personal use, you’ll have to determine what your DNA testing needs are.
- Paternity Testing
American Pregnancy Association
- Mitochondrial DNA
National Library of Medicine, U.S Department of Health and Human Services
- Paternity Proceeding Establishes Parent-Child Relationship
ohio state bar association , Karen Riestenberg Brinkman
- Tribal Enrollment and Genetic Testing
Jessica Bardill (Cherokee), PhD, American Indian & Alaska Native Genetic Resource Center
- FIND A GENETIC COUNSELOR. National Society of Genetic Counselors (NSGC)