At-Home DNA Tests Might Not Be as Accurate as You Think…


Thanks to the modern miracles that are science
and the post office it’s possible to get just about anything in the mail now, from
uncooked meals to DNA tests to a wig for your dog. And while I could talk about dogs in wigs
all day, this episode is actually about those DNA kits. Just how accurate are they, and how much stock
should you put in the results? Private companies have offered these DNA tests
for over a decade, but recently they’ve gone mainstream. We even had an episode where Trace and Amy
tried them out. The concept is pretty simple, you just spit
in a tube and send it off to a stranger, except this time they actually want your spit for
once. The company’s lab extracts your DNA from
the cells in your spit and compares it to DNA in their database. A couple of months later, you get a breakdown
of information about your ancestry, how at risk you may be for some disease, and a bunch
of other stuff. Such and such percentage from Africa and a
high risk for maple syrup urine disease and so on. It sounds cut and dry but there are a ton
of asterisks along the way. First there’s the fact that only a small
percentage of your DNA is getting tested. You’ve got over 6 billion base pairs in
your 46 chromosomes (go you) and they get passed on randomly from your parents. The results can vary a lot, even among siblings. One test of fraternal twins found one twin’s
DNA was nearly twice as British and Irish as the other. Obviously they have the same parents so they
have the same family history, but the DNA that was passed down to them and then tested
was wildly different. To complicate things further, there is no
one definitive gene from anyone that pinpoints where they’re from. Instead there are sets of genetic markers
that populations might share. Not everyone in that group will get all those
genes, and some people from other places may have some of the same genes by coincidence. So when you get your results back from these
tests and you see that you’re 25% european, it doesn’t mean one quarter of your ancestors
were european. It means a quarter of the genetic markers
they were able to test seem to be prevalent the most in Europe. Plus, the DNA you send in is not getting compared
to a massive representative sample — these companies are using as few as 115 people from
certain regions to define what the genetic markers of people from that region are. That’s not a ton of people, and remember
how much genes can vary even between siblings. So using these tests to trace where you come
from is fuzzy at best. But they do have another compelling use: identifying
if you carry the genes for certain diseases. Again, this topic isn’t as straightforward
as you might think. These tests can identify if you have genes
associated with certain diseases, but they can miss minor variations to the genes, leading
you to think you’re not at risk for a disease, when in fact, you are. But even if you do test positive for one of
these genes it doesn’t mean you will 100% get that disease, it just means you are more
likely to get it. You are at risk, and you can pass that risk
on to your children. If you take a DNA test that shows you carry
genes associated with parkinson’s disease, your risk of getting it is higher, but other
factors like age could have more of an impact than just having this gene. These results are nuanced, and it’s important
to go over them with a doctor who can walk you through what they really mean. These tests can be empowering and help you
learn about who you are and what your future might hold. But they’re less like the gospel truth and
more like a horoscope with more accurate results. I wouldn’t plan your entire identity and
future around one DNA test. Special thanks to our sponsor, Domain dot
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domain names and web hosting when you use coupon code SEEKER at checkout. Trace and Amy actually tried these DNA tests
to show you just how they work. To find out what percentage of Trace is sasquatch,
check out the video here. Did you get your DNA Tested? What were your results, and how serious do
you take them? Let us know in the comments, subscribe for
more, and thanks for watching Seeker.

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