What DNA ancestry tests can — and can’t — tell you

What DNA ancestry tests can — and can’t — tell you


So I recently took one of those at-home DNA
ancestry tests. All I had to do was fill up a vial with a
disgusting amount of spit and mail it off for analysis. We’re gonna be here for a very long time. I just spit it back up in my nose. A couple weeks later, this is what I got:
It’s a neat little pie chart with these specific percentages that were color-matched to different
regions on a world map. The report told me I was mostly Southwest
Asian — no surprises there, considering both my parents are from Iran. That percentage — 86.7% — I understood
that to be the portion of my DNA that’s West Asian. But it turns out, that’s not exactly what
ancestry tests are telling us at all. This is an ad for one DNA ancestry test, 23
and Me. An ethnically ambiguous woman travels the
world, and a circle animates around her, sort of like the pie chart in my test results, as
if to say, this woman’s DNA is 29% East Asian. And here’s an ad for
a different ancestry test. “52% of my DNA comes from Scotland and Ireland.” And somehow this information compels him to… wear
a kilt? Alright, so what are ancestry tests really telling
us? Can you help me understand what my results are telling me? Because I’m getting mixed messages from
ads and how other people talk about their results. This is Wendy Roth. I’m an associate
professor of Sociology at the University of British Columbia. OK. First of all, these test results are not
about your entire DNA. They’re about a tiny, tiny fraction of your
DNA. To understand how genetic ancestry tests work,
let’s start with the DNA itself. There are about 3 billion base pairs in our
genetic code. Those are the As, Cs, Ts, and Gs that form
the instructions that make us… us. Of these 3 billion base pairs, 99.9% are exactly
the same in all humans. But for the remaining .1%, one person might
have an adenine where another person has a guanine. These single-letter differences are called
Single-Nucleotide Polymorphisms or SNPs. Groups of SNPs can help explain why some people
are taller than others or why some people have green eyes while others have brown eyes. But most SNPs have no known effect at all. What many DNA tests are looking at are a relatively
small number of SNPs, specific positions in this .1% in our DNA, in order to give you
your results. When a testing company receives your sample,
they compare your pattern of SNPs to
different reference populations in their database. These reference populations contain SNPs known
to exist more frequently in different modern populations in the world. Then the testing company will give you a percentage that represents how strongly your pattern of SNPs resembles that group. But this process has a bunch of important
limitations and this is where things get complicated. Lots of markers are found in multiple
populations around the world. First, even trying to classify humans into groups in the first place is tricky. Human genetic diversity isn’t organized
neatly into groups like countries or continents. Take a look at the distribution of this SNP
that affects how a person absorbs folic acid. It’s commonly found in Mexico, but also
in Chile, or even China, just as often. So let’s say that a particular marker is found
in the South Asian population 30 percent of the time. There’s still a possibility
that when you inherited this marker you got it not from somebody who was South Asian, but
from somebody who was in some completely different group that also happened to have that marker. Second, testing companies put together their
reference populations based on academic research and other people that have taken genetic ancestry
tests. And most testing companies aren’t clear
about how many people are represented in their reference populations. So each company might have different reference
databases, which helps explain why you might get different results from different companies. So what does this all mean for my results? This is a probability with a margin
of error. So it’s not that you overall are
eighty-five percent West Asian, but that the particular spot that they happened to look at,
eighty-five percent of those locations are associated with Western Asia in their reference
population. So what about these other results? Am I really 2 percent African? You’ve got a lot of, you know, sort
of small trace percentages here. Percentages that small are really not meaningful,
again because that could be affected by having one person in the database. And if that one person gets reclassified later
on because they get a larger sample, that percentage will disappear. Ultimately, DNA ancestry tests are really
just giving us a probability, the testing company’s best guess. And that uncertainty isn’t made very clear
in the results. Buried in my results I found this “confidence
slider.” It turns out, my results were presented at
about 50% confidence by default. When I increased it to 90%, my results got
much more vague. All of a sudden I was “broadly” West
Asian and a lot of my genetic markers were unassigned. So, DNA ancestry tests don’t actually tell
us where our ancestors lived – they’re really just giving us probabilities of where we’re
likely to have relatives today. But so what if people misinterpret their results? Well that has consequences. They can make us believe that our ethnicities
have these bright-line distinctions between them, like in a pie chart. When people are presented with
test results and these percentage breakdowns and they are led to think that these tests
can tell you your race or they can tell you who you are, that that leads to a way of thinking — makes us feel that there are very stark and clear biological differences between races. One study found that DNA ancestry tests reinvigorate
age-old beliefs in essential racial differences, that our socially constructed racial categories
like “white” or “black” are essentially different from each other. Some groups have even turned to genetic ancestry
tests to try and prove their “racial purity.” DNA ancestry tests can be useful. Search YouTube and you’ll find hundreds of
stories of people using them to find lost relatives and fill in their family histories. And, to people who don’t know a lot about their ancestry, the tests offer the best available
estimate. But it’s important to remember that, despite
their marketing, these tests are just a company’s best guess at matching your genetic markers
to different parts of the world. What they’re not going to tell you is whether
you should wear a kilt or not. DNA ancestry tests might not be as informative
as you want them to be, but more and more people are still taking
them. And this giant database of genetic information is
becoming super valuable to an unexpected group: Law enforcement. We’ve teamed up with Verge
Science, to look into how your privacy is at risk because of genetic ancestry tests, even if you’ve never taken one.

100 thoughts on “What DNA ancestry tests can — and can’t — tell you

  1. We did our first collaboration with our friends at Verge Science to explore how at-home DNA tests are putting everyone at risk. Check out their video here: https://youtu.be/7q8Oa97a04g

  2. I hate the use of the word "race" as opposed to using the right word "ethnicity". We are one race, the Human Race and that race is made of many Ethnicities.

  3. This is what you need to keep in mind: Genetics is not certain. Right now, the field is finally getting the freedom to do "trial and error", and they are using these tests to perfect the BASELINE of human ancestry.
    5 years ago, no government would allow a company to gather genetic samples from people either aound the world, or even a controlled, tight village.
    It is a sicence field that is fighting to experiment. The same way Elon Musk blows up 20 rockets before getting the 21st to land safely, these tests experiment with 20 million samples so, one day, they can get the 210 millionth sample to be nearly 100% accurate.

    My point is: they are not lying to you. They just BEGAN to have the freedom to take off with these population-wide studies, and these tests are helping to lay the ground work database for a further perfected analysis in the next decades.

    Don't let genetic studies die out, fellow humans, it is a wonderful field that really needs the stigma to be taken out of it so they and we can experiment more and more freely in order to categorize with certainty every piece of our genome.

  4. In Somali culture you are taught to count your male relatives by name. much more accurate that ancestry.com 🙂

  5. I had this DNA test done… I found out I'm from earth…yay!…love this content, keep up the great work

  6. basically everything the govt has told you is a lie. All parties lie,it's how they get money from lobbyists.

  7. The CBC (Canadian Broadcasting) had identical twins take DNA tests from all the available companies. Not one company gave them identical results. Some were very different. Also, You Do Not Own Your Results. The companies can sell them to pharmaceutical companies or give them to the police – hope Uncle Jim never left his DNA at a crime scene.

  8. We are now not only giving out their information for free online but also sending them our DNA!
    The world is crazy. What is privacy right? It's 2019!

  9. 23 & me ALTERED my daughter's DNA/hapla group from being EXACTly same as mine to thousands of year back ~ @ time our ancesters lived in Tartia/Russia/Siberia. IS? this to please some "ONE WORLD Government" ___Scam?

  10. if you want a genetics scientist instead of a professor of sociology to tell you the same thing watch this video
    https://www.youtube.com/watch?v=Isa5c1p6aC0

  11. Fortunately my parents came from WASP backgrounds which practiced the recording of 'family Bibles', seven of which go back nearly 300 years. No DNA test necessary..

  12. At 2:40 you can see that you are way past the fill line with your spit. It's hard to take you seriously when A) You didn't read the directions, B) You don't follow directions, or C) You did this for dramatic affect.

  13. I know this is kind of off topic but my friends dad found his long lost brother when their DNA matched on one of those kits. Idk pretty cool.

  14. Cant believe people are so stupid to believe those commmercials lmao.
    First time seeing them as i dont watch tv.
    Both of those people were so ignorant. Well plus the millions of others

  15. I wish I knew this before I paid over $100 for this a few years ago. The price has doubled since then. Don't do it.

  16. The rule in the Old South was a drop of African blood makes you African,”. But now that the drops can be measured, “it sort of made race seem a lot more arbitrary.
    Still, those drops have had a potent effect on people’s identities. For some whites, even a smidgen of African ancestry was commonly referred to as “the taint,” said Harvard University African and African American studies professor Henry Louis Gates Jr. “That said it all: that it was something to be ashamed of, something dark and dirty.”

  17. When I glanced at your 90% (vague) results, for a moment I thought it said you were 100% "Danish". I'm a nitwit (97%)
    @,:¬ o- huh??

  18. No Central or South America with the Lego models?? Another reason why I will never do this. There's a smaller database for us and I'm not going to contribute to their data for free. They should be paying EVERYONE to do this for them.

  19. First, on "Shemites" and Semites- your DNA analysis might say you have jewish ancestry, which would most likely be descendants of Shem, before his descendant Eber, the first semite was born.  Your report might say you have west Africa ancestry, which may not clearly specify that it is Caucasian- Hamites, specifically… the Amber (Caucasian) Race originated farther south than the very white Caucasians; the Bible is a history of the Amber Adam/Eve lineage; the very white Adam/Eve were actually named Ask and Embla, from an Eden much further North.  There were five Edens.  My advice is don't get scientific DNA analysis- all the medical association wants to do (generally) is sterilize you; make you frigid, impotent, infertile… so that they can have Increase in their special elite ranks, while suppressing increase in yours!

  20. Asking a sociologist instead of a geneticist about DNA testing… Classic Vox focusing mostly on presentation rather than good journalism

  21. My parents have red skin my grandparents have red skin me red skin results? eastern european? My grandmother was born on a Navajo Indian reservation.

  22. They know nothing about east Africans esspically Somalia Djibouti Ethiopia horn of Africa basically

  23. This shows why we need national health care in the US. The more samples these companies generate and share, the more the health care INDUSTRY will discriminate. They won't be open about why they decline coverage, they'll invent some plausible excuse to discriminate, and even though you have some sickly, at-risk relatives you may never be sick a day in your life. Great for you, but say you're in an auto accident at fault by another driver and you have no coverage? Well, welcome yourself to the growing number of Americans being bankrupted by a greed based medical system. Expect all your insurance coverages to skyrocket as your credit ratings plummet (how my risk as a driver is suddenly compromised by my inability to pay medical bills is a head scratcher), you will never be able to buy another big ticket item again, even though car ownership is pretty much a given in most of the US in order to work and have a normal life. Goodbye to any thoughts of putting kids through college or hoping to leave any kind of inheritance and the injustice now becomes "generational". Single payor (good riddance to health insurance companies, hmo's, credit collection agencies, high six-figure salaried administrators and slews of middle men responsible for making US health care the most expensive in the world) health care is the only option (unless hospitals return to being charity based, non-profit entities they way used to be) to keep millions of Americans from becoming a hopeless underclass. To all those right wingnuts screaming foul to socialism and returning to the "good old days" (when that was someone might have to explain to me what made that elusive period so good), I can tell you this one truth, we are stronger as a nation and people when we had a healthy prosperous middle class with a few millionaires than we are today with a burgeoning hopeless army of the working poor and obscenely wealthy billionaires. This idea propogated by the one-percenters, that only the rich can provide the capital to create new jobs is ridiculous to the insane. America became great because enough people had enough time and spare money to tinker with an idea in their garage and pursue the American dream. People who will never, NEVER, see their situations improve have been duped into being the gnashing, snarling rotweillers that protects a policy that is systematically disassembling America's middle class. These are the very same people that still tenuously have the power to improve their lives and that power comes in the form of the vote.

  24. There ARE biological differences between the races. (((Intellectuals))) want to tell you that races don't exist.

  25. I took the test and it came back N/A because I'm native American and my peoples were nearly wiped out lol jk

  26. Who in there right mind would do this! This test could get you in so much trouble! Your insurance company could use this against you! You could be framed! If you have killers in your family! You never let anyone have your DNA

  27. Why not do all the major tests and show the differences and a specialist talking about the top 3-5 simultaneously, instead of just 23 and me?

  28. Apparently my DNA has no knowm matches. There were traces of silicates, chlorophyll, and ice cream.

    That was one wild Saturday night.

  29. Is there scope for them realistically to become more accurate in the near future? Sequencing a whole genome, for instance, might be easier to do in the coming years and, perhaps couple with richer database, may offer us a chance at a greater, more bespoke understanding of our own ancestry. Great video, thank you.

  30. 3:13 "First, Even Trying To Classify Humans Into Groups In The First Place Is-"
    Me: RACIST
    "Tricky"
    Me: No.. It Can't Be..

  31. Genetic test: “You’re 0.4% Ashkenazi Jewish.”
    Literally any white non-religious person: “Oy vey! Baruch ata Adonai! Dreidels!”

  32. I dunno I just don't feel comfortable sending my DNA into the internet! Like I assume they keep a record of all of it and that freaks me out

  33. I don't think I'll ever take one. I know my ancestors are from Africa. I'd like to know exactly where, but I don't think I will ever find out

  34. The bell curve is real. Races differ in ability. FACT. We are fundamentally different people. Everything else is just sophistry.

  35. Lol a majority of everyone's dna is the same as every other organism's dna. I should've been telling everyone I'm 70% palm tree.

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