The thing about identical twins is that their DNA is identical. That is not up for debate and it is a simple matter of biology. So when not one, not two, but three sets of identical triplets and quadruplets made a guest appearance on the the popular television show “The Doctors” to have their DNA tested, it seemed like the results were sure to be a foregone conclusion. You are not going to believe what happened next until you watch this video.
Dr. Phil McGraw’s daughter in law, Erica, is special. She happens to be an identical triplet. Just one in sixty thousand pregnancies result in identical triplets, which occur when one fertilized egg splits, and then one of the zygotes splits again.
Erica and her sisters were one of three sets of identical triplets that appeared on the popular syndicated television show “The Doctors.” while on the program, they all agreed to take a DNA test, which of course should have yielded very predictable results. But something crazy happened.
The three sets of identical triplets each used a different DNA testing company, 23AndMe, Family Tree DNA, and Ancestry DNA. The results? In every case, the tests came back with dramatically different findings about the sisters’ ancestry.
As anyone who has taken high school biology knows, the DNA between siblings would be significantly similar, and with identical twins, triplets, and quadruplets, it should be similar enough so that general information about haplogroups should be exactly the same. And we also know that DNA is supposed to b 99.99% accurate in criminal cases. So how does this happen?
We turned to Familytreemagazine.com to find out why identical twins could have such varying results. As it turns out, DNA testing as a genealogical tool is very subjective when compared to forensic DNA testing.
Genetic genealogy is not as exact as forensic testing. It is heavily dependant on interpretation of results by a technician. The DNA does not lie, but the interpreter is making calculated guesses based on genetic patterns observed in populations. If different technicians look at three sets of results that are identical, without knowing that they are identical, they may evaluate the results differently.
Further, even the criteria for making these educated guesses is still in question, because science still does not have an agreed upon definition of genetic ethnicity. In other words, there is only one race: the human race.
Even if you could say with certainty that you had a specific ethnic background, the percentage in relation to other ethnicities present in your DNA would still be a matter of interpretation.
Forensic DNA testing is a completely different set of processes, and is also far more expensive to conduct. It does yield a far higher accuracy of profiles it generates, and can be considered legally accurate enough to convict or exonerate a defendant.
So, When Erica and her sisters got their test results and found out that their ethnic backgrounds didn’t line up as closely as you’d expect, it has far less to do with their DNA than with the tests and interpretation of the results.
Have you ever taken a DNA test to research your heritage? As compared with other research like family histories, how accurate were the results? Please share your stories with us here.