Genetics – ancestry testing companies can do better

For just £79, companies offer tests that claim to connect people with long-lost relatives, uncover family history, or expose lurking danger in the form of susceptibility to disease. They are presented as an empowering way for individuals to discover their past and take control of their own health. But the marketing and discussion surrounding direct-toconsumer genetic testing are at odds with their delivery in many ways. Genetic tests for both ancestry and health risks can be unreliable tools for consumers of colour and may reinforce incorrect notions of race and ancestry.

Genetic testing companies have a customer base of eager genetic sleuths from many different backgrounds and they market accordingly, with results of varying success. For example, a 2019 Ancestry.com campaign invites Canadian consumers to “uncover the lost chapter of [their] family history” over dramatised footage of a Black woman and a white man eloping. The ad, set in the antebellum American South, suggested a narrative many viewers found overly romanticised. Wired documents numerous falsities in the ad, including the idea “that most mixed-race people in America today descend from loving, consenting relationships” and that “the North was some promised land of equal opportunity.”

Ancestry.com swiftly pulled the ad, but it remains an example of the optimistic premise most ancestry testing services are based on. While many consumers will be pleasantly surprised by their results, the potential to uncover violence always looms: it just doesn’t make for a very inviting advertisement. Dig deeper and it becomes apparent that genetic testing’s plight is much worse than a 30-second ad spot.

People of European ancestry make up more than three quarters of genetic study participants despite accounting for less than one quarter of the world’s population. These are the studies that genetic testing companies use to develop their services. Ancestry testing compares the DNA sent in from a customer with DNA of known ethnic origins. To provide accurate results, the company must compare tiny variations in a consumer’s DNA with a database that can indicate which variations are common in which ethnic groups.

Companies such as Ancestry.com have their own databases which diversify along with their customers but still currently give much finer detail on European ancestry than other areas. Ancestry.com separates Ireland into a whopping 85 populations, for example, in comparison to nine for the entire continent of Africa. With this in mind, it’s clear to see why they’d court Black Canadian consumers, an underrepresented demographic in genetic studies whose interest would increase not just their revenue but their accuracy as well.

The problem of representation in genetic databases extends to healthcare. In 2001, a “reference genome” was compiled from numerous donors who responded to a 1997 ad in a Buffalo, New York, paper. Supposedly representing the entirety of an “average” human genetic code, the idea was to provide a comparison that scientists would use to comb through a patient’s genome for potential causes of illness. However, 70% of the genome was sourced from a single donor (whose ethnic background is unknown). Furthermore, the underlying theory is also skewed, as it’s impossible to condense the genetic variation of humanity into a standardized genome.

Scientists regularly face issues when comparing their patients’ DNA to the reference genome, such as struggling to find a diagnosis and overlooking significant genetic mutations. One study found that almost 300 million base pairs of DNA were present in 910 African American subjects but absent from the reference genome. This count is disputed by some experts, but many geneticists agree that the reference genome has such large gaps that it is almost useless. To combat these shortcomings, many research groups, including one from the testing company 23andMe, have produced ethnicity-specific reference genomes for use in diagnostic medicine. But even these run into issues because many self-categorising individuals are mistaken or uninformed about their ancestry.

“Many geneticists agree that the reference genome has such large gaps that it is almost useless”

The lack of diversity in genetic databases means some companies do not offer equal access to their health tests. In 2019, 23andMe announced a new test for type 2 diabetes risk, developed using data from 2.5 million users. The move indicated a significant step away from the company’s signature ancestry testing but had some drawbacks. The test was found to be less accurate in people of non-European descent, who also happen to be more likely to be affected by type 2 diabetes. Established in 2017, Myriad Genetics only expanded its breast cancer risk testing services to “women of all ancestries” in 2021 and now provides information on their website regarding the struggle to provide accurate results for women of non-European ancestry.

It may seem surprising that these exclusionary tests get to market. Alicia Zhou, who heads research at Color Genomics, explained: “To be only able to offer a product to one part of the population is inequitable and should be unacceptable to the field,” however, “holding back data from individuals that could benefit” would also be wrong. Unfortunately, those people of European ancestry who are most likely to benefit from a test such as Color Genomics’ often have better access to healthcare already. Ethnic minorities, while more likely to experience poor health than white British people, have inconsistent access to healthcare and are also more likely to report a poor experience with it. The lack of diversity within these companies’ existing databases thus has the potential not only to provide inaccurate ancestry testing results, but also to exacerbate existing health inequalities.

If you’ve been paying attention, you might have noticed the careful language that companies use when describing their tests. “Ancestry” and “ethnicity” are not the same as race, but consumers are, to some measure, expected to extrapolate. Mark Thomas, professor of evolutionary genetics at University College London, calls it “shifty”. These companies encourage our collective interest in ancestry and categorisation but avoid using the word “race” because their tests can’t –and won’t – tell you what race(s) you are. That is dependent on how you are perceived by society, how you’re raised, and how you yourself feel. We conflate the differences in appearance between people that we use to assign races, such as skin colour, with genetic differences, despite the evidence.

The science overwhelmingly suggests, as explained by biologist Joseph L. Graves, that “there is no single physical trait or gene that can be used to unambiguously assign people to racial groups.” It is simply too difficult to find enough racespecific differences to warrant applying the informal category of biological race to humans. Biological race exists – it’s been found in other animal species, such as chimpanzees –but the same level of genetic difference has not been found in humans. Rather, race in humans is a social and political category.

Despite these issues with access and accuracy, the genetic testing industry is a great place to begin deconstructing our society’s ideas about biological human differences. Taking an ancestry test can overturn individuals’ ideas about their own race: those who take ancestry tests are more likely to identify as multiracial, or, at the very least, adopt more specific identifiers. This demonstrates the fluid nature of our understanding of race and the potential of genetic tests to impact it. A Duke University study found that white Americans were significantly less likely to express racial essentialist beliefs, such as “certain races are smarter than others because of genetics”, when they’d been given background information about genetics and race before taking a test. This suggests that, with proper education, taking a genetic test can demonstrate the flaws in racist ideology and help change people’s mindsets.

In order to become a positive addition to popular science, genetic testing companies should be honest about the groups they serve and explicitly reject the false notion of biological race in humans. Including more clear, comprehensive information on websites regarding a test’s development accuracy is a good way to help potential users make informed choices about what test to use and evaluate what they really want to get out of it. Genetic tests can still be valuable resources whether you’re looking for medical insight or a long-lost relative. But before you buy, consider if you’re really getting your £79 worth.

Charlotte (she/her) is a first-year biological sciences student