• The Listener
  • North & South
  • Noted
  • RNZ

DNA testing can reveal your ancestors – but it's not always what you expect

Photo/Getty Images

The easy availability of DNA testing has prompted millions to shake their family trees, but what falls out is not always welcome.

Bernard Philpott thought he knew his family story. By the age of 67, using old-fashioned sleuth work and genealogical websites, he’d mapped out his British ancestry and traced his Irish family back to Limerick and Dublin. But when he took a DNA test in 2016, Philpott discovered the facts of the matter: he was 40% Irish, 37% English and – surprisingly – 2% Māori.

Now, looking at a photograph of his mother when she was young, he says she looks part Māori. “But my mother never said anything about a Māori connection. No one ever did. And I have a suspicion my father didn’t know.”

Macro alias: ModuleRenderer

Documentary evidence to fill out the picture painted by the DNA test results was hard to find, not least because marriage certificates held at the historic Rangiātea Church in Otaki were lost when the building was razed in an arson attack in 1995. But subsequent research has found that, in 1861, his great-great-grandfather Horace Broughton married Maryanne Hamilton, possibly of the Ngāti Hauiti iwi. Philpott’s DNA test could now link him to Ngāti Hauiti lineage, including a potential connection, through another Broughton marriage, to entertainer and Poi E producer Dalvanius Prime. The DNA discovery both confirmed a suspicion and opened a new line of inquiry for Philpott, who loves music and sings in a choir.

Now 69, Philpott is one of millions of people spitting into test tubes or swabbing the insides of their cheeks in the hope of finding a missing branch in their family tree or an unexpected last chapter in their personal history.

According to a recent report from Credence Research, the global direct-to-consumer genetic-testing market was valued at US$117 million in 2017 and is expected to hit US$611 million by 2026 as shoppers rush to buy services and testing kits for information on family lineage, disease risks and personal traits.

Bernard Philpott's mother. Photo/Philpott family

Who’s your father?

The results of genetic tests can be life-changing. DNA sleuths have tracked down siblings or half-siblings they never knew they had or found their father was not the man they called Dad. In its latest estimate, US genetic-testing business 23andMe says 7000 users of its service have discovered unexpected paternity or previously unknown siblings.

The results of a DNA test, supported by anecdotal evidence, confirmed suspicions for an Auckland woman that she is the daughter of a high-profile Catholic priest in the Auckland Diocese, now deceased. As she told RNZ National this month, “It wasn’t a surprise, but knowing the reality was overwhelming.”

Speaking anonymously, she told the broadcaster she had made contact with Coping International, a private online group for children of priests growing up with their “guilty secret”. “It is so much better to know the truth. I couldn’t possibly go back to where I was; I am much happier knowing who I am.”

Now, she says, she just wants written acknowledgement from the church that she is the daughter of a Catholic priest. Bishop of Auckland Patrick Dunn told RNZ he has seen the evidence of paternity and accepts that the woman’s father is who she says he is. The woman, now in her fifties, does not want to reveal her father’s identity, but she is thrilled that the church will now formally acknowledge she is the secret child of a supposedly celibate priest.

DNA tests have also solved the problem of mistaken identity. Alice Collins Plebuch, the 69-year-old daughter of an Irish Catholic family in New York, had always wondered why there was so much evidence of European Jewish, Middle Eastern and Eastern European ancestry in her genetic heritage. Last year, she solved the mystery. After months of research and further DNA testing of close relatives, she discovered that her father, Jim Collins, had been sent home with the wrong family just hours after his birth in 1913. Jim was born to Jewish parents but mistakenly given by the hospital to an Irish family, whose own child was sent home with the Jewish family.

Alice Collins Plebuch, pictured with a second cousin, solved the mystery surrounding evidence of European Jewish, Middle Eastern and Eastern European ancestry after months of research and further DNA testing of relatives. Photo/Getty Images

The cost of curiosity

Most DNA test-takers are simply curious, excited by the science and the technology that give them the tools to unpick their family histories, says Brad Argent, ancestry spokesman for Ancestry.com, the world’s largest for-profit genealogy company. But often, he says, they dive in without preparing themselves for what can be a “very intimate and personal experience”.

For those from a small family and those who were adopted or the result of a sperm donor, “suddenly, they take this DNA test and they get matched with cousins. For the first time in their life, they have this notion of family. I have watched people become someone else when they get those results. It can be quite transformative.”

But not everyone wants the past barging into the present: a birth father with no inkling his one-night stand 20 years before resulted in a pregnancy, the sperm donor assuming his decades-old contribution to humanity was done and dusted, and the parties to a brief affair hidden from censorious eyes may not welcome that reconnection.

Others just don’t want to know. When Japan-based English-language teacher Antony Brett Shaw claimed that former Cabinet minister and Auckland mayor John Banks was his birth father, Banks refused to have a DNA test. Last year, the High Court ruled in favour of Shaw’s paternity claim. Justice Patricia Courtney said Banks’s refusal to undergo a DNA test was an admissible fact “from which an adverse inference could be drawn”.

The dead, in contrast, have no such right of refusal. In 2012, mitochondrial DNA – DNA passed down the maternal line – was used to identify a skeleton buried under a car park in Leicester as that of King Richard III. Interest piqued when researchers at Leicester University compared the body’s Y (male) chromosomes with those of living descendants of Edward III, a great-great-grandfather of Richard III. There was no match. Somewhere in the family history at least one man had been cuckolded. Media speculated on the legitimacy of the Tudor dynasty, but researchers were nonplussed: according to the university, the false paternity rate is about 1-2% in any generation.

A model made from the recently discovered skull of British king Richard III. Photo/Getty Images

Filling a cap

Most people forking out $100-500 for a DNA test will not have the OMG moment of learning of an unknown parent, a secret sibling or a cuckolded ancestor. But for many, the process fills a nagging gap in their family story.

Coral Shearer, who lives in Paeroa, had never been able to identify the family of her great-grandmother Mary Ann George (later Vickery), who arrived from London in 1870. One of her children’s birth certificates said she was born in Scaldwell, Northamptonshire, but after trawling through censuses and church records, even visiting the cemetery, the ancestry case remained cold.

Then, 18 months ago, she had a DNA test and was able to contact suspected relatives in the US (some DNA testing companies provide space on their websites for clients to upload documents, photographs and entire family trees). As a result of the relatives’ research, she was able to unlock the story of her great-grandmother (she was the daughter of barge gypsies, whose horses pulled barges along canal towpaths) and extend her family tree from the mid-19th century all the way back to 16th-century England.

“It does mean a lot. I knew all about [my great-grandfather’s] family, but it stopped at her. I wanted to know what her family was like and why she came out here. I’m slowly building up a profile of her, putting meat on the bones on what their lives were like.”

A reconstruction made from the skull of “Cheddar Man”. Photo/Getty

The science simplified

The search for surprise, for completion or for Māori or Viking or Salem-witch uniqueness is driving the private genetic-testing industry, but how much can we actually take from these selected snips from the complex helix of our DNA?

There are three genetic clues to your ancestry. Your mitochondrial DNA (mtDNA) contains your maternal ancestry passed down unchanged in orderly fashion from mother to daughter through the centuries – although sons receive their mother’s mitochondrial DNA, they cannot pass it on to their children. The Y chromosome or Y-DNA provides information about your paternal ancestry passed down from father to son.

Slight genetic changes or mutations in mtDNA or Y-DNA can become traceable markers of descent passed down through family lines and whole populations moving through time and place. These inherited markers identify different haplogroups – genetically related populations that share a common ancestor – from a particular geographic region up to tens of millennia ago. These ancient bio-geographic female and male lineages track genetic continuity back to just a few sets of divergent populations, famously described by University of Oxford geneticist Bill Sykes as the Daughters of Eve and the Sons of Adam.

Ancient DNA from a 166 cm tall, lactose-intolerant Mesolithic hunter and gatherer who died in Somerset, England, some 10,000 years ago has forced a dramatic change in modern Britons’ ancestry and knocked a whopping hole in white supremacist ideologies. First unearthed in 1903, the so-called Cheddar Man – his skeleton was found in a cave in Cheddar Gorge – has the genetic markers for blue or green eyes, brown hair and “dark to black” skin pigmentation usually associated with sub-Saharan Africa.

According to postdoctoral researcher Tom Booth working at the Natural History Museum, “Cheddar Man subverts people’s expectations of what kinds of genetic traits go together. It seems that pale eyes entered Europe long before pale skin or blond hair, which didn’t come along until after the arrival of farming.”

Today, about 10% of British ancestry can be linked to this population of hunter-gatherers who migrated to Europe about 14,000 years ago, including that of local history teacher Adrian Targett, found to be related to Cheddar Man on his mother’s side.

The other main DNA-deciphering approach, autosomal DNA testing, looks at genetic material inherited from both parents. This material identifies individuals with whom you share one or more common ancestors up to about 500 years ago. Autosomal tests also provide information about an individual’s “ethnicity” by identifying sections of the DNA that match reference databases of modern populations. Some gene-tracking companies, including 23andMe, follow these threads back to Europe 20,000 years ago and Africa a couple of hundred thousand years ago, giving clients a tantalising quotient of Neanderthal DNA.

It makes for an interesting pub chat, says Argent (Ancestry.com does not go that far back), but from a genealogical perspective it is not particularly informative, he says.

Retired history teacher Adrian Targett believes he looks like Cheddar Man.

“DNA cousins”

Most companies supply some form of map or pie chart describing your quotient of sub-Saharan African, European, East Asian, Oceanian or Native American genetic make-up. This information can be used to draw up lists of what Ancestry.com describes as “DNA cousins” – other clients on the company database with a similar DNA reading in a kind of genealogical Facebook.

As a way to find people who share your DNA, these tests are useful, but there are limitations. The information provided by autosomal testing is limited to a process called genotyping, whereby scientists select parts of your DNA that tend to be different. Single nucleotide polymorphisms or SNPs (pronounced “snips”) are the most common type of genetic variation among people. A genealogical DNA test will sample several hundred thousand of these, then compare or match them with others on a company database. But this is only a fraction of the 10 million SNPs estimated to be in the human genome, leaving a lot of information untested.

And the reliability of ancestry DNA results is restricted by the size of the database each company uses. The 23andMe DNA database, for example, has more than three million customers; Ancestry.com has more than six million. But these tend to be dominated by test-takers in the US and UK respectively.

“If you are from a small region of South-east Asia or Africa, where not many people have done the Ancestry or 23andMe test, you are not going to get a great result,” says Nic Rawlence, lecturer in ancient DNA at the University of Otago. “On the other hand, if you are from Europe, you should get fairly good results because lots of Europeans are doing the test.”

In any case, ancestral DNA tests represent only very small chips off the ancestral block. A mitochondrial DNA test will undoubtedly tell you something about your mother’s and your mother’s mother’s line, says Rawlence, “but follow that line back 10 generations and you are learning about one of more than a thousand ancestors in that line alone”.

Similarly, Y-chromosome testing traces only one line of a person’s male ancestry, starting with a man’s father, his paternal grandfather, paternal great-grandfather and so on. Of a man’s 64 great-great-great-great-grandparents, a man shares his Y-chromosome with just one.

“If you break it down, you get 50% of your DNA from each of your parents,” says University of Otago biological anthropologist Lisa Matisoo-Smith. “That’s 25% representing your grandparents, 12.5% representing your great-grandparents. Pretty quickly you get down to pretty minuscule amounts going back a few hundred years. By 600 years ago, everybody living today with western European ancestry would have shared ancestry somewhere there.”

A further drawback is the variation between the ethnic or bio-geographic labels companies use. Ethnicity estimates – and they are just estimates – work on a continental level, but they are not so good at identifying countries or regions. In some cases, seemingly very different ethnicities are genetically quite similar – Native Americans and people from India, for example, can trace their ancestry back to Central Asia, so they share ancestral genotypes, says Rawlence, which clouds the results. Sorting out the generations can also be tricky – those pie-chart percentages may refer to people high up in the leafy branches of the family tree or far down in the time-distant trunk.

And depending on what bits of DNA get tested and what genetic hand you have been dealt by your parents, the three times great-grandmother that you know was Southeast Asian may not have passed any of her genetic code on to you but may have passed some on to your sibling.

Oriini Kaipara. Photo/Maori TV

Chance discoveries

David Wilton, a sixth-generation New Zealander now based in Philadelphia, had a DNA test to find a connection with his great-grandfather. A photograph and a found marriage certificate hinted at the possibility of his being part-African. He was disappointed when his results showed no African ancestry, but he discovered a kink in the family tree: through family records posted by a “DNA cousin”, he found the family of an illegitimate son born to one of his mother’s aunts and put up for adoption – although still, mysteriously, present at a family picnic in 1900, after the adoption. Pooling their research, Wilton and his previously unknown relatives were able to link to a branch of the family they never knew existed.

“It’s interesting, but in terms of how you connect with the current world, I am fairly ambivalent about what it really means,” says Wilton, on the phone from Philadelphia. “I’m slightly suspicious of people creating their identity from some sort of bloodline. We should be looking forwards, not backwards. If you have a really diverse family tree, maybe you feel more empathy for the human race, but then maybe you should feel that anyway.”

Native Affairs presenter Oriini Kaipara had a similar experience of incomplete ancestry in 2016 when she took the Ancestry.com DNA test as part of a story on Māori identity. The following year, Argent gave Kaipara the surprising news that she was 100% Māori, even though she knew she had at least one European ancestor on both her mother’s and father’s sides. In explaining the findings, Argent said that over time, genetic material passed down to her had just “diluted away. In your case, it’s led to you being 100% Māori.”

But Matisoo-Smith, one of the investigators in National Geographic’s Genographic Project that aims to map prehistoric human migration patterns through DNA samples, asks how we define Māori. “At what point did Māori become Māori? Can you tell Māori from Polynesian or other east Polynesian populations? We are talking about only 750 years of people being isolated here. Where do you draw a line between Māori and Cook Island Māori or Tahitian?”

Speaking from San Francisco, Argent uses a playing-card analogy to explain the results. “When you have two people who want to create a child, each has a deck of cards. When they want to have a child, they each shuffle their deck and deal out 26. It is theoretically possible that each deck of cards could be entirely black or entirely red. You could have a mother who is 50% Māori, and when you are conceived, she doesn’t give you any of the genetic markers that relate to her Māoriness. But you could have siblings who get all of it. You have these echoes of your ancestors, but it depends on the genetic lottery.”

The result of that lottery, he says, does not define who you are.

“You could identify with Māori but have no Māori DNA. It is about cultural identity and connection beyond what is inside you genetically. It is part of the story of you, but it’s not all of it. You are also the sum of the stories you learn, the traditions that have been passed down. Whether you are adopted or part of a birth family, those things still influence who you are as a person.”

Last year, curator and editor Lana Lopesi was looking to authenticate a story she had been told of one of her great-great-grandfathers, a Chinese labourer who had worked in Samoa. Her mother, she knew, is English-Canadian; her father Samoan. As she wrote at the time, her biggest fear was finding out that she was more than 50% European. “It’s not that I don’t want to be white … It’s more that being white will change completely who I claim I am: a Pacific woman.”

Her DNA test result showed her to be French, Italian, Serbian, English and Portuguese – not a trace of Oceania. As she says, “I’m whiter than the milkman.”

Lopesi knew this was wrong. Both her parents, all four grandparents and one great-grandparent are still alive. She knew their stories. She heard their laughter.

Lopesi says the results have encouraged her to put more trust in the stories passed down by her parents and grandparents. “But I have friends who have no family, and they really hold on to the DNA test – that is what really scares me. When you think of DNA in terms of the Holocaust, of blood quantum [theories] and what that means for indigenous people, the desire to constantly be proving ourselves – I know people it has helped but there are misconceptions about what you can get out of it.”

Antonia Prebble. Photo/Getty Images

Sleuthing stories

For most DNA delvers, including those who have had a DNA test, there is still a place for good old-fashioned sleuthing: combing documents, reading books, talking to older relatives, sharing oral stories. Even TV series such as DNA Detectives, says Rawlence, rely on teams of genealogists digging through traditional family histories behind the scenes.

“I seriously doubt that you need DNA to reveal the family history of some celebrities, such as [Kiwi actor] Antonia Prebble’s distant family relationship to Diana, Princess of Wales. It is one tool in the toolbox that allows you to help work out your family history. But a lot of it is a gimmick: if you go back far enough, you are related to everyone. Singer Stan Walker’s 0.1% Native American DNA is so tiny it’s homeopathic compared with the 1.5-2% Neanderthal DNA we all, except those of sub-Saharan African descent, carry in our genomes. So you don’t want to do DNA testing in isolation: you want to do it in conjunction with all the other family history detective work that you do.”

In 2008, old-fashioned family sleuthing took Brian Oliver to Devon, to the family farm and flour mill where generations of Olivers lived and worked, even after his ancestors left for New Zealand in 1841. The strangest part of the visit, he says, was that it didn’t feel strange at all. He reported feeling “quite at home, quite at peace”.

An intriguingly high Scandinavian score in his DNA test is now prompting him to explore his mother’s side of the family. Whereas his father’s forebears were mostly farmers, his mother’s family line is dotted with business people and bank clerks. For the former telecommunications technician and business owner, this made complete sense.

“I thought, ‘Ah, that is where I get what I am.’ Until I researched my mother’s side, I thought I was an odd one out in the Oliver side, but I can now see where I get my interest.”

The information we can extract from our genetic code fills in the big picture – Matisoo-Smith is using analyses of ancient DNA to track the origins of Pacific peoples – as well as the pixel-sized personal story of what makes us us, down to our wonky smile, bald pate or even lifestyle choices.

Unhealthy predictions

Already, DNA test results are being used to determine diet and fitness advice: the wine we should drink, the exercise regime we should follow, whether we can have five espressos a day or a single decaf. DNA readings are also driving the growth of personalised medicine. Variants in genes have been found to identify patients who metabolise certain drugs too rapidly for them to work or too slowly, leading to toxicity.

But the use of DNA testing for disease diagnosis, couched in vague phrases such as “higher risk” or “low probability”, is being blamed for fuelling both false assurance and unnecessary panic. When 23andMe was launched in 2007, with backing from biotechnology powerhouse Genentech and Google, it offered customers information not just on their ancestry but also on their genetic predisposition to certain diseases (and baldness, and earwax consistency). But in 2013, the US Food and Drug Administration (FDA) declared a moratorium on 23andMe’s health reports, saying the company did not have the evidence to back up its disease-risk predictions.

Since then, the FDA has relented slightly, giving the company the go-ahead to report on customers’ risks of developing just 10 conditions, including coeliac disease, late-onset Alzheimer’s and Parkinson’s. But, as GP Margaret McCartney, author of The Patient Paradox, told the Guardian last year, having certain genetic variants does not mean you will develop a particular condition.

“These companies often say that it’s worth it for the helpful advice. But I can give you really good advice right now without seeing a single test result: be active, have lots of social networks, do work you enjoy, try not to smoke or drink too much, don’t be overweight or underweight, eat lots of fresh fruit and vegetables. Nobody needs to get tests done to get that kind of basic lifestyle advice. I think people are being made anxious by manipulative advertising.”

23andme’s website does state its Genetic Health Risk reports “are not for diagnosis. Factors like lifestyle, environment and genetic markers not covered by this test can also play a role.” And even if a health warning is valid, we might not take the information on board anyway. Recent research in the US found that when people were told of their genetic risk for certain diseases, they did not rush to change their diet, quit smoking or take up exercise. “Expectations that communicating DNA-based risk estimates changes behaviour,” the authors concluded, “is not supported by existing evidence.”

Not-for-profit group GeneWatch UK says “genetic horoscopes” are a bad strategy for health. The health impacts of smoking, poor diets, poverty and pollution, it says, are not limited to individuals with “bad genes” and can be better addressed through preventive strategies such as better sports facilities, healthier school meals and banning fast-food advertising aimed at children. It also accuses such tests of cultivating a market for “preventive” medicines among the worried well and shifting the blame from unhealthy products or pollution to “bad genes”.

The bottom line is that genetic data tells only one part of our individual story. As with health and fitness, writes Rawlence, our ancestry and family trees are far more complex than a simple chart or reading.

“Family trees are not nice, tidy trees, but rather a thick, interlaced bush. Only by using all the available tools can we begin to reliably reveal hidden family mysteries.”

This article was first published in the February 24, 2018 issue of the New Zealand Listener.