Who are you? Where you come from? How we identify ourselves is at the heart of what it means to be human, and the ability to get easy, fast, and affordable answers to these questions has made the genetic testing market worth nearly a billion dollars a year.
The best DNA test kits give you detailed, personalized reports on… what, exactly? Where did your ancestors come from? Not really. They tell you where your DNA came from today, which can help you research your genetic ancestry and ethnicity, but they certainly don't provide the magic bullet you might think. Here's how DNA tests work, their pros and cons, and how to choose the one that's right for you.
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What are DNA, genes, and chromosomes?
Deoxyribonucleic acid (DNA) is made up of two long molecules that carry the genetic instructions for cells to function and reproduce. DNA is in all living things. It is arranged in a "double helix" of two strands that wrap around each other. Sections of these strands are called genes, which determine particular characteristics. DNA exists in the nucleus of each cell in the form of chromosomes. There are 46 chromosomes in each cell, 23 from each parent.
However, exactly how DNA is inherited is random. Members of the same family, including twin brothers, can inherit different segments of DNA from their parents. Cousins share DNA and if you sign up for a DNA testing company's cousin matching service, you may see your genetic matches appear. Getting third cousins and DNA isn't much help. Go back several generations and you may not share any DNA with some of your ancestors.
DNA test kits and what they tell you
DNA test kits collect your saliva or cheek swabs, which is then sent to a laboratory, which extracts your DNA. Essentially, you spit into a tube or swab each cheek twice with a cotton swab. What you get in return, whether in the mail or more likely online, is information that seems to indicate where your ancestors came from. In short, a breakdown of your genetic ancestry; your ethnicity
But DNA test kits don't tell you where your ancestors came from. Human history is the history of migration, so trying to place your genetic ancestors in one geographic location is inherently problematic.
So how does the process work? Segments of your genome are referenced against each other in a database, freely assigning different pieces of your DNA to geographic locations. Companies also tend to use reference samples from people who have four grandparents in that region, pooling similar DNA samples from a particular location. This helps produce a likely connection to a location over long periods of time, but a lot of assumptions are made. Your results may not be unique.
DNA test kits require a cheek swab or saliva sample, which is then sent to a lab (Image credit: Elizaveta Galitckaia/Shutterstock)
However, you will receive information and visuals about general populations and regions to which your DNA links. For example, you might know that you are 81% European, 9% Asian, but in this data you might be told that you are 41% English and 40% Welsh, for example. These are estimates based on the size of the company's databases, as well as the algorithms and statistical techniques they use.
You may also be told that you are related to specific other people who have also taken a DNA test with that company, with matching cousin being the most common product.
DNA test kit companies and why use more than one
Industry-leading genetic companies include AncestryDNA, LivingDNA, Family Tree, MyHeritage, and 23andMe. Once you've run a test and gotten the results, you can usually upload your raw DNA data to another testing company to take advantage of their databases and algorithms.
DNA test results are becoming more accurate as databases expand and software improves (Image credit: 23andme)
This is because the results you get will vary. Over time, the databases of different companies become larger, and therefore better, with the addition of data from new locations, while the reference populations used for particular regions also become larger and more reliable. . Algorithms, software, and AI are also improving. That's why the results you get from a DNA test kit today are so much more detailed than when they first became available a decade ago, and they'll be better in the future.
It's also worth knowing that, until recently, DNA testing companies served people of European descent better, simply because they were more popular in North America and Europe.
The three types of DNA tests
There are three different tests for genetic genealogy, each of which reveals different facts about your ancestry:
Autosomal (atDNA) – This is by far the most common and useful DNA test for ancestry and is often referred to simply as “family finder” or simply “your ancestry”. It can give anyone their ancestry up to around seven generations and is useful for cousin matching. Therefore, all DNA testing companies use it as their default offer.
Chromosome (yDNA): This test uses the Y chromosome, which is found only in males and is passed down through the paternal line. Mutations in a man's yDNA can link him to a genetic population with which he shares a common ancestor.
Mitochondrial (mtDNA): This traces your maternal ancestry. It can be taken by anyone. Mutations in your mtDNA can link you to a genetic population with which you share a common ancestor.
Choosing the Right DNA Test Kit for You
Many DNA test kits offer genetic readings on your ancestry as an entry-level product in a broader offering designed to help you investigate your individual family history. It also matches his DNA to new clients, so it can give you new information years after the first cheek swab you took.
Here are the basic differences between the most popular services, all of which offer autosomal tests by default, but head over to our article on the best DNA test kits for more details:
AncestryDNA – uses a saliva test and has a database of 20 million, the largest of all, and provides access to 30 billion genealogy records for family tree research.
Live DNA - uses a buccal swab and has a database of a million. It claims to have data from all of Africa and therefore promises better results for African Americans and African Europeans. He also specializes in British ancestry.
DNA Family Tree: Uses a cheek swab and has a database of 1,4 million, so it's not the best for cousin matching. For an additional fee, you can also reference your DNA with their yDNA and mtDNA databases.
MyHeritage DNA: uses a buccal swab and has a database of 4,5 million. It also offers access to 12 billion historical records and syncs everything with your family tree search.
23andMe: Costs €99, uses a saliva test, and has a database of 12 million, the second largest. So good for cousin matching, 23andMe also offers health results.
Are DNA test kits worth it?
DNA test kits are not a scam, but you should be aware of their limitations and realize that they are actually consequences of much larger ambitions. For example, researchers are using anonymous DNA test results to create maps of human migration patterns (opens in a new tab), but also to develop population-based personalized healthcare, in part by identifying people at risk of genetic diseases. For population genetic modeling, the growth of DNA test kits is great news.
However, what DNA test kits do not do is give simple, fast and 100% reliable information about the origin of the ancestors of a specific individual. So if you're researching your family tree, get a DNA test kit and incorporate the results into your own research. But if you're just looking for a quick DNA-based sense of identity, confirmation of your own unique heritage and ancestral roots, DNA test kits won't give you enough accuracy for that.
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