What do DNA kits actually tell us about ourselves? As it turns out, quite a lot!

At one point or another, most of us have likely wondered whether our love for pizza is because one of our ancestors hailed from Italy, or if a crippling fear of heights is a genetically inherited trait. DNA testing kits promise to hold the key to all the mysteries we have about ourselves from our lineage to our genetic makeup, and even our ice cream preferences! These kits have skyrocketed in popularity with over 40 million people having tested their DNA. Both of my parents are part of this number, and their results were incredibly revealing.

How do these tests actually work and how can a small sample of saliva reveal so much? After parting with anywhere between £40 to £150, you send off a tube of spit and the lab technicians get to work. They begin by extracting DNA from the tube and measure specific positions in the genome using a microarray (a small rectangular chip). This tool measures different locations in the genome.

Human DNA has small differences unique to each individual – variants – and this is what the scientists are measuring. They use chemical enzymes to separate the DNA into single strands and smaller fragments which then enter the microarray. The microarray contains thousands of spots of DNA strands – some are normal and some are genetic variants. If you have one of these variants, your DNA will then bind to that specific spot.

One generation back you have two parents, two generations back you have four grandparents, meaning with every generation your number of ancestors doubles. Once you go back to the 12th century, roughly 30 generations ago, you have a whopping one billion ancestors

Your data is then compared to different reference panels with the variants associated with different ancestries. Once a certain variant is found, it is noted down and ready for your ancestry breakdown report. Different companies have different reference panels and methods, hence the slight variation in your ancestry breakdown when using different companies. Your ancestry report may also fluctuate as reference datasets improve, and more information is gathered.

Once your report is ready, what do the results themselves mean and what can they tell us? One of the most exciting parts is looking at historical matches and discovering who we are descended from. DNA researchers can sequence the DNA of people who lived 100,000 years ago using the 10,000 plus ancient DNA genomes available. Companies like 23andMe allow customers to compare genomes with historical people. A genetic match with someone from medieval times sounds pretty cool, but it actually means surprisingly little for your genealogy. One generation back you have two parents, and two generations back you have four grandparents, meaning with every generation your number of ancestors doubles. Once you go back to the 12th century, roughly 30 generations ago, you have a whopping one billion ancestors. At this point, your ancestors include most people from your population who lived back then, so technically everyone alive is genealogically equally related to all medieval people. From these billions of medieval ancestors, you actually only inherit DNA from a tiny fraction of them and have a mere 2,000 genetic ancestors from the 12^th century.

Who your genetic ancestors are is completely based on chance, but sharing a DNA fragment doesn’t necessarily connote anything special – you’re not any more genealogically related to that specific medieval person. Genetic matching with people from several hundred years ago may not be that revealing, but if you’re more interested in a historical person from around 200 years ago, then DNA matches can be fairly informative. If you match with someone from the 18^th century, your genealogical relationship is more specific than the rest of today’s population.

My perspective and experience with DNA kits is fairly unique and felt rather like an episode of Long Lost Families

Matches aside, the other main section of your DNA report is health which can detail carrier status, predispositions, traits, and more. Genetic testing can be precarious with false reassurance given or unnecessary panic about a variant. Bill Newman, chair of the British Society of Genetic Medicine, warns that these tests lack “clinical utility”. He also urges people to have intensive counselling before and after genetic testing. Margaret McCartney, a GP and author of The Patient Paradox, identified that “people are being persuaded to have these tests done, and they get results back that are very often of very low value and dubious helpfulness.” She also expressed concern that “the companies make their profits and walk away, letting the NHS sort out all the fallout, the push-back, from the test results.” Rather than focusing on a dubious health report, we should strive to live a healthy lifestyle. With that said, a lot of the data on kits like 23andMe appears to be mostly harmless, breaking down traits like earwax and muscle composition. 23andMe offers customers the choice to unlock more serious results and provides lengthy disclaimers explaining that these are not diagnostic results and that clarity should be sought from your GP.

My perspective and experience with DNA kits is fairly unique and felt rather like an episode of Long Lost Families. Growing up, my mum was unaware of who her father was, and one Christmas my dad and I gifted her a DNA kit from AncestryDNA. She sent off her sample and after a few weeks, we received the results. Her ancestry report revealed her father – my grandfather – was 100% Irish, and from this she worked out who he was. A DNA kit allowed my mum to uncover a whole new part of her identity and find the answers she had been seeking for many years. Last year, she met her five half-sisters for the first time. This technology was truly life-changing for my family.

There are lots on the market at varying price points and accuracy levels. You first need to decide what you want from the testing kit – are you more interested in the health side or where your ancestors are from?

My dad didn’t have any major family mysteries to uncover but he decided to follow suit and take a DNA test using 23andMe. His ancestry report revealed he was 94% British and Irish, 3% French and German, and 1.5% Scandinavian. Not the most exciting results, but it was still interesting nonetheless to see where my ancestors hailed from. 0.1% was unassigned, so perhaps there is an exotic part to me, albeit small.

If you’ve decided you want to take the plunge and uncover your family history, or perhaps instead find out if coffee will make you jittery, now you face the dilemma of which test to get. There are lots on the market at varying price points and accuracy levels. You first need to decide what you want from the testing kit – are you more interested in the health side or where your ancestors are from? I found that 23andMe was notably a lot less specific when breaking down locations. Ancestry pinpointed the exact location in Britain and Ireland where my ancestors were from, whereas 23andMe couldn’t even differentiate the percentage breakdown between Britain and Ireland. Read reviews of kits and conduct thorough research into a kit’s accuracy before you part with your hard-earned cash, as many kits are priced above the £100 mark.

DNA testing kits can’t provide all the answers, but they can be incredibly informative, especially as this technology develops and improves. These tests should be no replacement for proper health screening, and if you are concerned about what diseases you may carry, consult a medical professional. Also, be mentally prepared for what the test could reveal for both your health and your family as you never know what a small tube of your spit may uncover.