Thoughts

The validity of DNA Testing to Trace Your Family Heritage

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Are you interested in discovering your heritage or who your family ancestors are? If so, do you know where to start? And is the use of DNA testing via a home DNA test kit a valid mechanism to determine your historical race and origin? 

All of these questions are valid and deserve a considered answer. Therefore, by way of answering these questions, let’s consider the following points.

The science of ancestry and DNA ancestry tests

At the outset of this article, it is essential to consider how valid DNA ancestry tests are when tracing your ancestral roots. 

Identical twins have virtually identical DNA. Thus, it is reasonable to assume that if both members of a set of identical twins sent in a DNA sample, their results would be identical. However, this isn’t necessarily correct. 

Evidence gathered during a recent investigation by the Canadian Broadcasting corporation demonstrated that twins don’t always get the same results when the samples are sent to the same company. And, across the genetic testing industry, the results of an individual’s ancestors can differ significantly from company to company. 

 For instance, if we return to our identical twin scenario, a genetics company told the one twin that she was 13% Broadly European. Simultaneously, the second twin’s sample showed that she was 3% Broadly European and had more DNA matches to specific European countries and regions. What is even more curious, the twins sent their DNA samples to five different companies, and each came back with a different result.

Why? 

 The concise answer to this question is that no one really knows. In his article titled “The limits of ancestry DNA tests explained,” Brian Resnick” cited a computational biologist’s response to this scenario. Ergo, the results were “mystifying.” 

Does this scenario invalidate the use of DNA tests to determine your ancestry? 

When asked, genetic scientists note that as a whole, “discrepancies in ancestry testing doesn’t mean that genetic science is a fraud and companies are making up these numbers.” These discrepancies have to do with the limitations of science and critical assumptions that genetic testing laboratories make when analyzing DNA to determine the individual’s ancestry.

Moreover, the results from these DNA tests are based on estimates that vary between laboratories. And all of these results have built-in error controls. Secondly, your results from the same company might change over time, especially as the company gathers more data and signs up more customers. 

In summary, Wikipedia.com defines a genealogical DNA test as a “DNA-based test which looks at specific locations of a person’s genome, in order to find or verify ancestral genealogical relationships or (with lower reliability) to estimate the ethnic mixture of an individual as part of genetic genealogy.”  

 Individual laboratories get different results because they use distinct ethnic group markets and genetic matching algorithms. Therefore, ethnicity estimates for an individual will vary between laboratories or companies.  

The validity of DNA testing 

Therefore, the question that begs is whether DNA testing to trace your family heritage is worth the effort. 

By way of answering this question, let’s take a quick look at how the tests are done. 

  1. Take a genetic sample

There are several different ways to do this: spit in a test tube, while another is to take a small round brush, similar to a hairbrush, and scrape the skin cells off the inside of your cheek. 

The human genome is humankind’s complete set of DNA. Each DNA molecule comprises two twisting, paired strands, consisting of 4 nucleotide bases, Adenine, Thymine, Guanine, and Cytosine. Adenine pairs with Thymine, and Guanine always pairs with Cytosine. A DNA strand is considered a base pair. The human genome contains approximately 3 billion of these pairs, residing inside the 23 pairs of chromosomes within every human cell’s nucleus.

When this sample arrives at the testing lab, technicians do not look at every single base pair found inside the 23 pairs of chromosomes. Instead, they speed up the process by looking at the locations on the genome that vary between people from different geographic locations. 

  1. The DNA is compared to other people’s DNA with known ancestries

Once these differences have been identified, the next step is to compare these variations or single nucleotide polymorphisms (SNPs) to known reference groups or other people’s DNA with known ancestries. The caveat here is that, while these reference groups should be the same across all laboratories, this is not necessarily true. And these reference groups often change. 

The way genetic testing laboratories determine your ancestry is by comparing your SNPs to a control group’s SNP based on geolocation and ethnicity. DNA ancestry laboratories can pinpoint DNA to specific European countries.

Final thoughts 

While, on the one hand, it looks as though testing DNA samples to trace your ancestry and family heritage is not worth the time, money, and effort. However, on the other hand, it will give you a broad indication of what your ancestry is. If your heritage is predominantly European, your results will include a detailed list of which European countries.

 

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