Tuesday, January 16, 2018

DNA Testing for Heritage and Ancestry Is, Simply Put, Inaccurate

You go to take a cholesterol test, and your doctor, very thorough, sends you to four different labs.  One reports your cholesterol is 200, one says it's 180, one says 150, and one says 130...

After a car accident, you get go to four different body shops for quotes.  One says your car's paint color is taupe; one says it's sea blue; one says its ocean blue; and one calls it sea green...

You whip out four different rulers to measure your foot.  One says it's 12 inches; one says its 6; one says 8; and one says 9...

In all of these scenarios, you would make two conclusions:

1.  These test results (or body shops, or labs, or measuring sticks) are not that scientific!

2.  At least three -- and likely all four -- of these results MUST be wrong.

These parables sum up the world of DNA testing for heritage or "admixture."

We've said it before, and we'll say it again.  But today, Kristen V. Brown, a writer for Gizmodo, published an excellent piece discussing the snake oil that Ancestry.com, 23andme, Gencove, FTDNA, and other labs are selling.

Simply put, these labs cannot tell your ancestry.  I repeat, they cannot tell your heritage, or racial or ethnic admixture.  The science just isn't there yet.  And it might never be.

Brown details how she got four different results from four labs.

She also alludes to, but doesn't state um, confidently enough, about the concept about being confident about your known results.

It's what I jokingly (and longwindedly) call the:

"I was born in a tiny isolated village in the Swiss Alps that has never been invaded.  I know my mom and dad, and there's a video of my birth.  I DNA tested them and they are my parents.  I DNA tested my grandparents too, and they are my grandparents.  There were no affairs and no invasions in my town.  I know my great grandparents too and I am their spitting image.  The church records state I am Swiss going back to 1400.  But HELP, this DNA testing service said I'm British.  Am I British?"  (Or Indian or French or Dutch or whatever) problem.

NO, dummy, you're Swiss...

I for one, always read the fine print.  23andme, for example, states clearly that it cannot spot German (or French) heritage 92% of the time!  Germans make up the LARGEST PLURALITY of Americans.  Americans make up the LARGEST MAJORITY of those getting DNA tests done.  Thus, and I only say this half facetiously: these companies are engaging in the virtual ethnic cleansing of ethnic groups, wiping them off the genetic map, with their statements on people's heritage percentages, that are simply inaccurate.  

And 23andme, is, as far as we can tell, the most accurate lab!

Anyway, kudos to Kristen V. Brown and the people she interviewed for explaining it in her Gizmodo piece.  We suggest reading it.


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  2. The thing here is not that the tests are inaccurate, but the way they are marketed (which is sensationalist and false a lot of the time IMO)

    Running these commercial tests through 3/4 diy calculators should ensure ancestry being pinpointed fairly accurately.

    The science is there- it's just how it's used which is the problem.