DNA ancestry tests are bullshit

Originally published at: https://boingboing.net/2018/09/25/you-are-not-a-viking.html


You mean I REALLY AM descended from Charlemagne? As well as King Tut and Boudicca? I knew that all along, of course. This book just shows that YOU are TOO!


i have taken part in one of the DNA tests, and at no point have they ever hinted that i am descended from anything special. what sort of crazy DNA companies is this book based on?


The genealogical parts (especially noble blood and such) are ridiculous but there seems to be some validity in identifying ethnic ancestry in connection with genetic disease traits (e.g. sickle cell anemia amongst those with African-American ancestry).

In addition there’s also value in the tests teaching the “racial purity” types a lesson:


Yeah, I read that one based on Cory’s suggestion right on these very pages on 4 AM MON, JUL 3 2017.
It’s great.
The part about consumer DNA tests is only a tiny bit though, it has much more to offer.
I recommend it to everyone.


My DNA test revealed that I am a gentleman and a scholar, and my kindness is exceeded only by my good looks.


Obviously they get murky at a distance, but a (non-blood) relative did one recently, and was reunited with a lost segment of her family.


As a genomicist, I think this sort of critique is conflating several different things, some valid and others not. Yes, it’s true that being descended from Charlemagne or Genghis Khan is not particularly surprising – the farther you go back in time, the number of modern day descendants of anyone who had a lineage lasting into the modern day becomes huge. And it’s true that there aren’t such things as “pure” Britons, French, Germans, etc. On the other hand, genotypes aren’t equally distributed across all parts of the Earth. The idea that you can make a reasonable guess as to the general geographical origins of your ancestors from your genotype isn’t “bullshit” or “genetic astrology”, and is fact how we know such things as the history of human migration out of Africa, for example.


Recalling a “Probability Zero” short from Astounding back in the '50s, which used this point to support “The Population Implosion.”

Certainly genes and the traits associated with them used to be more unevenly distributed than they are now. But even saying something like “you are 16% Mediterranean” implies that there WAS some sort of “pure” genetic ethnography in the past. I actually wouldn’t be surprised to see that this is explained in they results that they give people but they sure don’t explain it in their marketing materials.


Why on earth would I allow the government entities access to my DNA without a search warrant? And I don’t think you can convince me that they don’t have access to it because its not run by a government agency.

“Police said they checked the crime scene DNA against one of the genealogy sites that have lately become popular — databases filled with the profiles of people who have volunteered their genetic codes in the hope of discovering their relatives and ancestors. GEDmatch, a free service, confirmed that police used it to identify DeAngelo.”
source - https://www.washingtonpost.com/news/true-crime/wp/2018/04/27/golden-state-killer-dna-website-gedmatch-was-used-to-identify-joseph-deangelo-as-suspect-police-say/?utm_term=.3e4043958d44


Are you going to refrain from getting blood tests, or cultures when you visit the doctor? Sequencing is crazy cheap, and easy to do. You can’t help but shed DNA, if you want to keep the government from using the information in it, you’re going to need some new laws.

1 Like

23&me said that I am genetically 14% Joan of Arc in a past life.


…so is their right to ownership

I’ve been tempted, but I suspect they wouldn’t be checking for a match to the Ancient One, the Kenniwick Man. His DNA matched that of various samples from the Colville Reservation, where the distant cousins are.

People are lazy, so the companies offer DNA checking, and then people can “know” about their ancestors. It’s easier to swab than do research.

The specific family tree isn’t so important, it’s the history that goes with it. I knew one branch of the family tree when I was about 22, but it’s the past decade, I’m about to turn 59, that internet searches has turned up so much.

I’m torn, did we have lots of real value, or is it that we left lots of material? Because my family was prominent in Red River, including the “Rebellion”, and it feels like luck to have a “famous” family. But it’s only by looking that I found all that out. The specific names mean nothing, the history does matter. I can go through a random pile of “The Beaver”, Canada’s history magazine, and see articles about my family. I can find current relatives, or some who just died. I can see where my father’s middle name came from. I can tell a different history of the “Rebellion” and know that the popular history is lacking. I can wonder whether that quote from Sitting Bull where he says he knew my great, great grandmother’s brother is true.

The process of mapping a family tree may be more important than the results. I knew the end of one branch, I then was able to see how each connected over the past decade. But I know them as people because I’ve read what others have said.

It’s a history that was erased, my father never said anything, I wonder why. In retrospect I suspect the cousins knew, having access to our grandfather, someone I saw only about three times. But it’s also a public history erased.

It’ easy to find a famous ancestor if you go back far enough, but if you don’t do the work, you won’t find more recent “fame”.

Thank you. There’s nothing “bullshit” about finding out your ancestry via DNA analysis. If you extrapolate it too far, or misinterpret the findings, sure. But the ones my family has done hasn’t told us we’re descended from any kings or emperors, it’s just given us an ethnic breakdown and told us what genotype we’re in. Not bullshit.


I can’t vouch for all services, but the well-known chromosome-number named service doesn’t partake in any particularly egregious inheritance fictions. However, like any complex data set, people will bring their own biases and misconceptions and use it to confirm whatever they believe to be true.

For users who cautiously approach the data with an open mind and an eye for the fine print will learn an important lesson: these tests (when used appropriately) don’t demonstrate how any one particular person or population is special. They show just how interrelated we all are.

But many people just want to feel special, or (worse) better than others. And there’s always going to be some jerk willing to sell them that “proof.”


Oh, those ancestry tests are stinking high bullshit. Let me explain why.

Consider genetic markers X and Y. Consider three population A, B, and C where A and B are large established civilisations while C is a small group living between both

You test several people in population A and B for both markers.

A people : X 20% Y 80%
B people : X 90% Y 5%

After that you sample the C population and find:
C people X 30% Y 75%

If you now conclude the C people are mostly related with A people with some B mixed in you make sense. For populations with known history and geographical spread factored in this works. For Populations!

Now consider person P of unknown origin. You test them and they cary X and Y. What do you know about their relation with A,B, or C?? Answer: nothing.

Remember both markers are found in all groups. Finding any marker in an individual tells you nothing because it could come from any group.

These ancestry tests use many more makers but the principle is the same; When they tell you you are 20% from Omnia all that means is that there is some probability that some of your ancestors were from Omnia. It can’t prove (or disprove!) they actually were.

See also: Prosecutor’s fallacy. The fallacious conclusion that what is shown to be most likely is also proven to be true.


The blood test you take at your local doctors office does not become part of a database accessible by the government.


**that you know of

seriously though, @Secret_Chimp is correct. Medical records have a lot more legal protection than most other information