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

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.

Comments

What if the same person submitted DNA twice

[aberglas]

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

Re:What if the same person submitted DNA twice

[HiThere]

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.

Re:What if the same person submitted DNA twice

[Tony Isaac]

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.

Re:What if the same person submitted DNA twice

[Tony Isaac]

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.

Re:What if the same person submitted DNA twice

[Antique Geekmeister]

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.

Why bother with twins?

[onkelonkel]

What is the point of the identical twins (other than adding click-bait value)? Why not submit two samples from the same person under different names?

Re:"Virtually" the same? Shockingly "similar?"

[Noumenal World]

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.

So the real question is...

[acroyear]

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

Re:So the real question is...

[Mashiki]

...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.

This is not full genome sequencing

[damn_registrars]

Some people don't realize that none of these services sequence the full genome. They sequence a collection of different sites as best they can (from the spit that you send them in a tube). Some sites will be sequenced really well and some not at all; it is the random nature of the system. What happens if twin 1 is sequenced really well at site ABC123 and has some rare mutation there but twin 2 is not sequenced at that site at all? They will assume that twin does not have the mutation - they will sub in "wild type" sequence at that locus as they won't have any thing better to go on - and you'll end up identifying them as being different. Take this many times over thousands of gene loci that they sequence and pretty soon you see how two identical twins can end up looking very different.

If you want to see how similar they really are at the DNA level, you need Whole Genome Sequencing (WGS) or at least you need to know what the coverage was at each locus for each twin. The former still costs thousands in most cases, the latter should be in the raw data (though they would need to convince the companies to release said raw data to them).

It avoids violating their terms of service

[Solandri]

e.g. Here's the relevant part of 23andMe's terms of service (emphasis added)

Furthermore you agree not to use the Services to: (1) [...]; (2) impersonate any person or entity, including, but not limited to, anyone affiliated with 23andMe, or falsely state or otherwise misrepresent your affiliation with a person or entity;

I suspect if a reporter did submit samples under different names, a court would side with the press against their terms of service. Eventually.

But by using identical twins, you sidesteps the possibility of wasting time, effort, and money because your report has been tied up by a gag order while a court mulls over what to do.

The opposite

[Lorens]

I'm reminded of the opposite story: someone forgets their password to the DNA site, and (instead of resetting the password) creates another account, sends in new DNA... and later calls their kid saying that it's incredible, wonderful, this DNA site has found that I have an identical twin somewhere!

Re:But Are They Real Twins?

[kinko]

99.8% between humans and chimpanzees refers to the entire genome (~3 billion base pairs).

23 And Me and related companies only look at about 3 million positions - the positions that are often different between different human populations/races (these are known as Single Nucleotide Polymorphisms).