Commercial DNA Testing Kits: Worth the Price?

May 12, 2020

By Rami Major

Commercial DNA testing kits are becoming increasingly more popular. Although they can be fun windows into our past, they can also have serious repercussions related to questions of privacy, crime, and health. 

Your DNA contains clues called markers, which are short sequences of your DNA that scientists have associated with different regions (like East Africa) and ethnicities (like Ashkenazi Jewish). Although this association is not exact, different companies can test your DNA to look for these markers and provide you with their best guess of where your ancestors are from. With a single swab of saliva, you can learn information about your ancestors from commercial DNA testing companies like Ancestry and 23andMe

A commercial DNA testing kit (Flickr).

If you’ve ever tried making a family tree, you know how difficult it can be to track down the names of all of your relatives. Commercial DNA testing gives you the option to find relatives with whom you share a small amount of your DNA, either through the company itself or through a public database where you can upload your DNA sequence (more on that soon!). You might discover a third cousin once removed or figure out the name of your great great great grandparent. 

Your family tree can include distant relatives like second cousins or third cousins once removed. Relatives who are further from you (“self”), like your third cousin, share less DNA with you than relatives who are closer to you, like your father or mother (Wikimedia Commons).

Increasingly, law enforcement agencies have been constructing family trees of their own to solve cold cases through the use of genealogy. As people get their DNA tested by private companies, they have the option to download their sequences and then upload them to public databases to find relatives. Law enforcement agencies have also begun to make use of these databases by uploading the DNA sequences of suspects involved in serious crimes to find people who might be related to the suspect. Matches found are usually related very distantly (think fifth or sixth cousin), so law enforcement agencies must painstakingly construct a family tree through other means such as Facebook and public records in order to narrow in on their suspect. These efforts have resulted in the capture of criminals like the Golden State Killer and John Miller (trigger warning: graphic description of violent crimes). Genealogy has also been used to track down the identities of unidentified crime victims.

Although genealogy has brought about plenty of good, from finding long lost family members to bringing justice to victims of serious crimes, there are crucial privacy concerns. Before using a commercial DNA kit, you should consider the possibility of uncovering difficult family secrets, like finding out about a different biological parent or unknown sibling. Additionally, policies have been slow to regulate the ways in which law enforcement can use DNA and genealogical databases. Can they employ these methods for serious crimes only, or can it be used for misdemeanors like shoplifting? Did the family member who law enforcement used to find the suspect consent to implicating them? Most services now require you to opt in to discover family members or allow law enforcement to use your sequence, but with no true rules in place, the ethical and privacy repercussions of DNA testing are questionable.

A scientist can compare the DNA profiles of suspects to the DNA profile found at a crime scene by looking at the sizes of the different purple bands in each column shown here on a gel (Wikimedia Commons).

In addition to giving you information about your heritage and linking you with new relatives, commercial DNA testing kits can also teach you more about your health. Your DNA influences everything from your response to caffeine to your risk for diseases like Parkinson’s. Companies look for parts of your DNA called variants. Like markers, variants are segments of DNA sequence, but instead of being associated with groups of people, they are associated with different effects on conditions or diseases. You could have a variant that makes you respond to caffeine quickly, while your friend might have a variant that makes them respond to caffeine more slowly. Although this health information can be informative, it should not be perceived as a medical diagnosis; commercial DNA tests can return false positives so it is important to consult with a professional before making any medical decisions. 

When you get your DNA tested, you can allow the results to be used for research. Scientists could compare your sequence to the sequences of other people to learn more about the variants that have an impact on disease. For example, a variant that is extremely rare in the population is more likely to cause disease than a variant that is more common. Although sharing your DNA sequence for research purposes can be incredibly helpful to scientists trying to understand diseases and find cures, privacy is a huge concern. Who exactly will be getting access to your DNA sequence, and could it be traced back to you? If so, it could expose sensitive personal health information. Further, would insurance companies or employers discriminate against you if they learned about your DNA sequence? Although some policies exist to protect consumers, they are not extensive. 

Commercial DNA testing kits can be an easy way to learn more about where you’re from and  who you are, but it is important to consider the consequences of genetic tests before you decide to get one for yourself. Would you use a commercial DNA testing kit?

Edited by Anna Wheless and Jeffrey Letourneau