The rise of DNA testing: you might find out more than you bargained for 

DNA testing is in fashion right now, most recently in the headlines because the documentary ‘Ant and Dec’s DNA Journey’ revealed that the legendary TV presenters are in fact distant cousins, and they both descend from the Vikings. The biggest brands of mail-in DNA kits, such as 23andMe, offer details about your ethnicity and family history, as well as what diseases you may have an increased risk of developing.

Many people receive the test as a gift, or order it for themselves out of casual curiosity, maybe some light hypochondria, or just a bit of fun. But what they find out is often life-changing. The news can be both positive and negative.

According to a recent Pew Research Center Survey, one in seven US adults have used a mail-in DNA test and 27% of those who had said they discovered close relatives they did not know about. The internet is littered with stories of people who ring up the customer service desk and insist they have been given the wrong results, only for the person on the other end of the phone to gently suggest that they talk to their parents about it.

Infidelities can be brought to light decades after the event occurred. It is also common for people to discover they were conceived through sperm donation. In the early days of sperm-donor technology, many parents kept it a secret because it was still stigmatised, and their children only discover they have a different biological dad when they take the test.

Some have predicted that the number of family secrets discovered through DNA testing will decrease in future generations; our grandmothers and great-grandmothers could never have predicted their extramarital affairs would be outed in the future, but these days people are increasingly aware that there is nowhere to hide from science.

CeCe Moore, a prominent genetic genealogist, said: ‘It’s getting harder and harder to keep secrets in our society. If people haven’t come to that realisation, they probably should.’

Sarah Zhang, who investigated DNA testing for the US news outlet The Atlantic, revealed some shocking cases: ‘I heard of DNA tests that unearthed affairs, secret pregnancies, quietly buried incidents of rape and incest, and fertility doctors using their own sperm to inseminate patients.’

She interviewed members of the private Facebook group ‘DNA NPE Friends’, the ‘NPE’ meaning Not Parent Expected, which includes over 1000 people who, after finding out that their parents are not who they thought they were, offer each other support through this unique discovery.

It’s not all bad; many people are delighted to discover a whole new family later in life, and for the children of sperm donors this can include dozens of half siblings. Shauna Harrison, a 41-year-old fitness instructor from California, had known for a while that she was donor-conceived when she went looking for relatives on 23andMe’s database in 2017.

Over the course of two years, she has gone from being an only child to finding 29 half-siblings. Many of them have met in person, and they even have a Facebook group to stay in touch with each other. Harrison is grateful for the discovery, saying, ‘You have a lot of the same history. It’s fun.’

On a more worrying note, The Guardian reported this year that DNA testing kits may falsely reassure those at risk of cancer. A study revealed that the majority of consumers who carry the gene mutation for breast or bowel cancer risk receive negative results in commercial kits such as 23andMe even though they are at risk.

The research also showed that many testing kits were not designed to pick up the mutations most often found in those of Asian and African American descent, and so it was disproportionately ineffective for people from minority backgrounds.

If you are thinking about investing in a DNA kit, or even buying one for a loved one this Christmas, act with caution, because you may learn much more than you thought possible.

Image: Tony Webster via

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