Media Starts to Gets Home DNA Testing for Ancestry Right -- Thank God!

Kristen V. Brown is back with an excellent piece for Bloomberg, on home DNA testing, that is remarkably astute for a piece in the popular media.  

It confirms much of what readers of this blog have seen posted here repeatedly.  It's so good, it's worth quoting at length:

DNA is great at identifying familial relationships like parents, grandparents, aunts, uncles and even second and third cousins. Beyond that, it gets fuzzy.

The genes that make you a superfast runner or that identify you as Irish are less well-studied. The accuracy of any one test depends on the data your DNA is being compared to. One 2009 journal article said consumer DNA tests were akin to horoscopes exploiting the human tendency to hunt for patterns in meaningless data.

So what does it mean when a test says I’m 25 percent Irish?

It’s a misconception that these tests can tell you where your DNA was in the past. 

If a test tells you that you’re 25 percent Irish, what it actually means is that you are genetically similar to other people who are a part of the reference data set of Irish DNA that the company has collected. 

Because each company uses a different algorithm and data set, your results may vary based on which company you use. 

In other words: Take all this with one very large pinch of salt!

Meanwhile, in Slate, appeared another excellent piece by John Edward Terrell.  Here's the quote for you to read for yourself:

Whatever the motivations, the current popularity of commercial genetic profiling worries me for two reasons. One is that these companies may be promising results they can’t actually deliver. 

The notion, for example, that our genes can be used to trace our personal ancestry far back into the past—say, to Genghis Khan, the Emperor Charlemagne, or one of the pharaohs of ancient Egypt—makes little statistical sense. You may disagree, but to me this comes across as selling something more akin to snake oil than science.

What worries me most, however, is that companies offering personal genetic testing customarily seem to report back to those sending along a sample of their spit that they are a mix of different “ethnicities.” This is more than simply statistical nonsense.

We are happy that the mainstream media is finally getting it right, instead of publishing starry eyed pop-sci nonsense about DNA tests.

Don't ever forget: if you come from Central Europe (France, Germany, Italy, or nearby countries), or if you come from a country where there are simply insufficient samples (much of the rest of the world), these DNA tests will wipe your heritage off the map, by telling you that you are something else.  Basically, they're most accurate at the Continental level, unless you happen to come from an island in Europe with massive amounts of people getting tested, i.e., the U.K.

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.