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Discover: So you want to have your DNA sequenced ....

Commercial DNA testing can be fun and accurate, but there are pitfalls you should be aware of, particularly when it comes to your privacy
DNA double helix. (stock photo)

Human nature is punctuated with a desire to understand. To understand the world, our place in it, as well as our place within our own bodies: what am I, where did I come from, and what is going to happen to me?

This need to understand ourselves, our pasts, and our futures could be why genealogy has become the second most enjoyed hobby next to gardening, and the second most visited category of websites, after pornography. 

Now that’s popularity. 

This devotion to tracking family trees has only amplified now that over-the-counter DNA testing kits are so prevalent; not only are they easy to take, but the test itself is relatively free of problems, says Dr. Thomas Merritt, geneticist and Canada Research Chair in Genomics and Bioinformatics at Laurentian University in Sudbury.

“DNA sequencing is super easy, this is not rocket science,” he says. “The accuracy of the testing is as good as it needs to be.” 

And the actual test-taking, usually a cheek swab or having to put a surprising amount of saliva into a test tube – 2 millilitres, or about a half teaspoon – is fairly straightforward. 

“Nothing is ever foolproof; the test is dependent on the fool who’s holding it,” he says. “But from my experience, it’s really hard to get someone else to spit in the tube that you’re filling.” 

So cross-contamination is not really an issue.  

The real issue with the DNA testing services now available comes down to privacy, and privilege.

Currently, companies providing consumer DNA testing are offering a wide range of services based on your sample: you can move beyond finding family members and into your ‘ethnicity’ – or ancestry composition as it is often referred to – and even medical testing for predisposition to illness and injury. In fact, there is one company that offers the chance to understand your best diet, physical fitness routine, ‘detoxification pathways,’ mental ‘wellness’ and even which supplements are best for you, all based on your DNA. And of course, they’d be happy to sell you the supplements they recommend. 

But how accurate can they possibly get with just DNA? That depends on who you are. 

Each company has access to public databases, as well as their own ‘data set,’ a collection of samples from every person that has used the company’s service. This information is compiled as each company’s proprietary data set. The more people who use a particular company, the bigger the data set they have, and the more accurate their predictions for your ancestral composition. 

For instance, when Dr. Merritt took three companies’ tests two years ago, he was amazed by the accuracy of the results, based on his understanding of his own family history. Not only did the results accurately show his family’s pattern of migration “within a couple of decades and fifty miles,” but it did so only from his DNA, with no additional family information. But, he says, that comes down to what they showed as his ethnic makeup. “The first thing they told me is ‘you are surprisingly white.’ Even for white people, you are translucently white.”

That’s because the data set for most of these companies is built from those who would have no issue revealing everything about themselves, “down to the base pairs,” as Dr. Merritt puts it. 

“I am a white male from middle-class United States,” he says. “I grew up in the suburbs of Connecticut, my dad worked in Manhattan, I went to a prestigious university and I was on the crew team. 

“I am the physical embodiment of privilege. I should be president of the United States. The system is completely designed for me.” 

He says this made him more apt to take the test, as the ‘system’ has never done anything to harm him. “If I was a person of colour, if I was a woman, if I was queer, if I was Indigenous, those are very different conversations.” 

There is a great deal of information that can be found out from DNA. For instance, the genetic component to sexual orientation. There is an allele (pairs or series of genes on a chromosome that determine the hereditary characteristics, such as hair colour) that when present means the person is 75 per cent more likely to be gay than the average population. Unfortunately, that’s information that could be detrimental to the life of the person behind the DNA – and reason to avoid the test in the first place.

And any attention paid to the world right now should give context to why people of colour would want to avoid sending their DNA to an outside source.

This will not only affect the accuracy of ‘ethnicity’ testing for those who are not reflected in the data set, but also in the medical aspects of what each company offers. 

The issues with the medical side are a bit more involved, but come down to sequencing, data sets, and our understanding of medical issues. 

Sequencing, the actual reading of DNA strands, would be looking at the six billion pieces of information in an individual’s genome – genome meaning strands of DNA. 

Between two people, there are six million differences. 

“Most of the differences are actually known, so there are a couple of hundred thousand differences that are really common,” says Dr. Merritt. “And so you don’t have to actually sequence the whole six billion points of information, what you have to do is look at those 250,000 spaces that are different … It gives you almost as much information, but it does so in a much more economical way.”

And if you’re highly reflected in the data set, you’ll get fairly accurate results from the 250,000 spaces. If you’re not, then your answers will be limited. 

For example: let’s say that within the data set, 99 per cent of people have blue hair, and one per cent have green hair. If the data set contains one million people to compare to, the sample will accurately reflect the makeup of blue versus green. If you only test 100 people, you only have a one-per-cent chance of finding the green.  

“That’s where the privilege comes in,” says Dr. Merritt. “If you want to identify markers for a specific disease, and we’re to look at this population and the disease happens in one per cent of this population, and we look at a million people to be pulled from, you’re going to find markers for that disease. 

“But if we’re now not doing white middle-class America, let’s say your family emigrated from Sri Lanka, and you’re female. You’re going to have a different genetic profile than I am. And you’re going to be represented by about maybe one per cent of that data set. Are we going to find those markers? We haven’t sequenced the entire genome, we’re looking for the markers that are highly variable. If you’re underrepresented in the data set, we don’t know what markers are more or less variable in the world population.”

And that’s not to mention the issues surrounding the current understanding – or the holes in that understanding – of the genetic component to diseases and disorders, as well as the recipient’s reaction to their test results. 

Some people may become obsessed with the information, and occasionally that could result in healthy lifestyle changes; in other cases you could have a smoker who refuses to quit because they don’t have a genetic pre-disposition to lung cancer. 

“Your average biological characteristic is about 10-per-cent genetics, so if I were to go through and look at a genetic predisposition for heart disease, I know that that predisposition for heart disease is going to give me a piece the story, and the fact that I had a fried egg sandwich for breakfast will be another piece of the story.”

While many of these companies are putting effort into increasing the diversity of their data set with programs and support, there is still the hesitancy to register such a personal part of you and your history with a company. 

Because security is a concern.

In addition to hacking, which is almost a foregone conclusion for personal data, the consumer DNA companies are beginning to partner with pharmaceutical companies, offering their data to them for research and development. Sounds like a logical partnership, until the possibility for impropriety sneaks in. 

Anyone who has read an advice column or heard from a friend who took a test might hear of a family blown apart by the results of a test showing siblings or unknown parentage. You might even be contacted by a long lost relative who recently took the test and found their connection to you. 

Or, despite having never taken a DNA test, you can be identified because a member of your family did: enter the Golden State Killer. Police had a sample of the serial rapist and killer’s DNA on file for years, but never anything to compare it to. Then GEDmatch offered the chance to look for even the barest of similarities to the police’s DNA sample. There was one. A partial match led them to search within the family of that match for a possible suspect, and he was arrested soon after. 

And while that is an amazing story of science stopping a horrific series of crimes, there is the other side of the coin: not only can 60 per cent of white Americans be identified in just the same way, regardless of their DNA sample status, but even anonymous DNA samples can be used to find not only the original donor, but their entire family, just by using the internet. 

Starting with 10 entire genomes publicly available as part of the international 1000 Genomes Project, researchers designed an algorithm to mine these genomes, all from men, for specific variations in the Y chromosome. After searching two consumer genealogy databases, as well as public records, the team identified five of the 10 research participants and their entire families, which were also part of the genome research project.

It comes down to this. If you are comfortable with the chance of identification, or having your data sold to a pharmaceutical company, then the consumer testing is an interesting way of finding out more about yourself, ‘down to the base pair’. But what that means in terms of accuracy – even as the companies specifically state their informational and entertainment only purposes – comes down to more than just how well you take the sample. 

It’s about your privilege in the world. 

Jenny Lamothe is a freelance writer, proof-reader and editor in Greater Sudbury. Contact her through her website,