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Identical Twins Test 5 DNA Ancestry Kits, Get Different Results On Each (www.cbc.ca)

Posted by BeauHD on from the junk-science dept.

Freshly Exhumed writes: Uh-oh, something is not right with the results of most popular DNA ancestry kits, as a pair of identical twins have found. Charlsie Agro and her twin sister, Carly, bought home kits from AncestryDNA, MyHeritage, 23andMe, FamilyTreeDNA and Living DNA, and mailed samples of their DNA to each company for analysis. Despite having virtually identical DNA, the twins did not receive matching results from any of the companies. "The fact that they present different results for you and your sister, I find very mystifying," said Dr. Mark Gerstein, a computational biologist at Yale University. Gerstein's team analyzed the results, and he asserts that any results the Agro twins received from the same DNA testing company should have been identical. The raw data collected from both sisters' DNA is nearly exactly the same. "It's shockingly similar," he said.

13 of 258 comments (clear)

  1. What if the same person submitted DNA twice by aberglas · · Score: 4, Interesting

    They should be identical. Will not be due to normal error. Or may not be even close due to incompetence.

    1. Re:What if the same person submitted DNA twice by mentil · · Score: 3, Interesting

      Just curious, is it possible that people are normally chimeras to some degree? It may not be 'error' so much as 'unexpected true result'.

      --
      Corruption is convincing someone that the selfless ideal is the same as their selfish ideal.
    2. Re:What if the same person submitted DNA twice by HiThere · · Score: 4, Interesting

      Well, women are all chimeras, but each cell should be the same as every other except for which X chromosomes are switched off, which appears random and is where the chimera comes from. And why all three color cats are female. https://www.google.com/search?...

      It *is* true that blood tests of women who have been pregnant can pick up small amounts of the DNA of the fetus...but that's *SMALL* amounts. And that's blood tests, where the last time I read these tests used either spit or a biopsy from inside the cheek. (That was awhile ago, however, so check before you believe.)

      There's also a small amount of expected mutation during development, so identical twins aren't really exactly the same. Somewhat well over 99% however.

      --

      I think we've pushed this "anyone can grow up to be president" thing too far.
    3. Re:What if the same person submitted DNA twice by Tony+Isaac · · Score: 5, Interesting

      Measuring DNA results is always an exercise in statistical analysis. Mitosis does not produce exact copies. Every cell division has changes from its "parent" cell. When labs test your DNA, they rely on a large sample size, and calculate averages. Your results at a specific location might be 65% AA and 35% TT. They are going to show a result of AA in this case.

      DNA results ARE meaningful, but it is necessary to understand what the results, and the algorithms, actually mean before making conclusions from them.

      I've been tested by 3 labs; several hundred (of 700,000+) of my results differed between the three labs. When this happens, we geneticists throw out the mismatches as errors. I've never seen this change any results in a meaningful way.

    4. Re:What if the same person submitted DNA twice by tlhIngan · · Score: 2, Interesting

      The raw results are not in question. The story itself says that the raw data was nearly identical, as one would expect. It is only the extrapolation of that data to infer ethic lineage that didn't line up so well.

      And that's the important point - the interpretation can differ. Yet if you look at all the ads, they imply an exact location. Spit in the tube and you'll find which neighbourhood your ancestors grew up in.

      Of course, your results are basically guesses by the site - if you ask it for your real location, the best it can give is your continent. If you want what you see in the ad, you get a guess.

    5. Re:What if the same person submitted DNA twice by Antique+Geekmeister · · Score: 4, Interesting

      There are apparently human chimeras who merged with fraternal twins in the womb to form one infant. One of the more bizarre but verified cases was Lydia Fairchild, who was found not to be genetically related to her children. The DNA of her cervical smear differed from that measured in other parts of her body, which helped establish her parentage of her own children.

  2. Re:"Virtually" the same? Shockingly "similar?" by Noumenal+World · · Score: 5, Interesting

    They're IDENTICAL twins, right? Why would their DNA be "virtually" the same? Why would there be ANY level of shock with that? ELI5 please.

    Because, for each test, there are some SNPs that the lab is unable to determine ("no-calls"). But these are going to be different for each individual, and in fact for each test an individual takes.

    There also are likely to be a very small number of SNPs that are simply read incorrectly.

    Because of these two issues, the raw results for the two identical twins will almost certainly not be the same -- although the results would have been identical if they had been able to get (correct) results for every single SNP.

  3. So the real question is... by acroyear · · Score: 4, Interesting

    ...are the professional forensic kits that law enforcement use as bad as this?

    --
    "But remember, most lynch mobs aren't this nice." (H.Simpson)
    -- Joe
    1. Re:So the real question is... by Mashiki · · Score: 4, Interesting

      ...are the professional forensic kits that law enforcement use as bad as this?

      Yes and no. There's been several labs both owned by police and private that have been caught using this same junk science shotgun approach in policing, leading to retesting 30 years back and people walking out the door. Back a few years ago when this was the hot shit, they only used 10 genetic markers, most have moved to 20-30 markers. Here's a case from NY State where multiple people were hit with fake tests, manufacturing DNA tests and so on. There was a huge push by justice dept's for DNA testing vs physical evidence because it was believed to be 100% perfect all the time.

      There's probably more people then you can think of out there these days who are innocent because they were hit with a "common match" because their family has lived in the same area for generations, or because the person doing the testing lied for whatever reason - and shit there are a lot of reasons people lie when they 'certify' a test.

      --
      Om, nomnomnom...
  4. Re: See, I told you we were different, Aaron! by Anonymous Coward · · Score: 3, Interesting

    Since you forgot to drop any citations:
    "western clawed frog, Xenopus tropicalis, has now been analysed by an international consortium of scientists from 24 institutions, and joins a list of sequenced model organisms including the mouse, zebrafish, nematode and fruit fly. What's most surprising, researchers say, is how closely the amphibian's genome resembles that of the mouse and the human, with large swathes of frog DNA on several chromosomes having genes arranged in the same order as in these mammals. The results of the analysis are published in Science this week1.

    "There are megabases of sequence where gene order has changed very little since the last common ancestor" of amphibians, birds and mammals about 360 million years ago, says bioinformaticist Uffe Hellsten at the US Department of Energy's Joint Genome Institute in Walnut Creek, California, a co-author on the study.

    That close genomic relationship doesn't hold true for all vertebrates, he notes. The zebrafish genome, for example, shows a much different gene order."
    Biologically we are all one big happy family : LIFE. Much of LIFE works very much the same way, be it cells, mitochondria, lung tissue or heart, muscle and bones, eating anf secretion, so no it really isnt that surprising to share DNA with other forms of LIFE as a whole.

  5. Re: See, I told you we were different, Aaron! by Anonymous Coward · · Score: 2, Interesting

    No, that's not how genetic testing is performed by these companies. There are anywhere from 10k-250k single-nucleotide polymorphisms (SNPs) that are tested by these direct-to-consumer ancestry and health products. The exact number depends on how many the genetics company decides to test, and for our purposes, not relevant anyway, except to say that it is several thousands. Testing these SNPs is not done randomly, they are targeted to specific genomic locations. To test that many SNPs from a single customer, the tests are performed on chips called microarrays, and these are mass produced so that every customer is tested on the same set of SNPs. (Some info on the chips and SNPs reportedly used by some of these companies can be found here: https://www.snpedia.com/index.php/Testing )

    So it may not be surprising that genetic tests between companies yield different results, but they should yield nearly identical results for identical twins when tested by the same company, directly because identical twins share >99% of the same DNA sequence.

  6. wat! And this just in, "two barometers in my house by eatvegetables · · Score: 3, Interesting

    Hey, just just bought two nearly identical barometers from crap-o-mart for $5 each. I put them next to each other in the same room. Imagine my horror when I noticed that their respective readings differ by as much as 10%.

    Oh, BTW, 23andme terms of service are clear, at least.

    "The laboratory may not be able to process your sample, and the laboratory process may result in errors ... Even for processing that meets our high standards, a small, unknown fraction of the data generated during the laboratory process may be un-interpretable or incorrect (referred to as "Errors" ..."

    Inexpensive direct to consumer DNA testing companies to not provide nor claim to provide results with statistically insignificant error rates. Don't we all already know this?

    The results are good enough to do fun things like find previously unknown relatives. To date, I've found three second cousins using 23andme. My ancestry information was likely not perfect but was accurate enough for intended purposes.

  7. Re:It avoids violating their terms of service by DocJohn · · Score: 3, Interesting

    No judge is going to issue a gag order after something has already been published. There's no reason to alert the companies ahead of publication with the exact details of your investigation. In fact, there's no need to even tell the companies ahead of publication. The only reason this is done to some degree is to get the BS public-relations comment that tries to explain away the discrepancy.

    Who is the reader going to believe? The DNA experts from Yale or some other university, or the for-profit company trying to defend their reputation?