Radio Review: The Business of Genetic Ancestry

'Genetics is messy and history is foggy. We are a species that is mobile and horny.' That is how Adam Rutherford quite accurately sums up the quest for understanding the human story in his documentary for BBC Radio 4, The Business of Genetic Ancestry.

Rutherford (no relation to Ernest Rutherford, the atom-splitting father of nuclear physics) is a journalist and geneticist who has taken extensive and hilarious exception to what he and many others see as the exploitative nature of genetic ancestry testing. Companies will, for a decent wodge of cash, unravel strands of DNA from a vial of your spit, compare them to other people's spit, and figure whom you might be related to. You could find previously unknown half-siblings or cousins - a powerful tool indeed - but this isn't where the problem lies. Some companies make claims about your 'deep' ancestry, churning out evocative and provocative results showing how you are a Celtic Viking Saracen descended from Charlemagne and Boadicea.

Rutherford's documentary tells us how such claims stretch the DNA beyond breaking point. He, along with fellow geneticists Mark Thomas and Mark Jobling, as well as genealogist Debbie Kennett, cover a healthy mixture of science and storytelling, giving listeners plenty of facts washed down with a handful of illuminating examples of how genetic ancestry tests can actually help people.

Properly used, genetic genealogy can be potent, helping fill in genuine, perhaps painful, gaps in a family tree, as illustrated early on in the show by the story of Julia, who spent 20 years trying to find her grandfather.

But it's the sometimes ludicrous nature of the business that makes headlines. The drive to profiteer gives these companies the incentive to find sexy results, selling as science what Mark Thomas calls 'genetic astrology nonsense'. Human sexuality is mysterious and, if you'll pardon the joke, fluid. Our mobility and 'horniness' lead to all manner of complications, but we love a simple story and will clearly pay a lot of money to hear one.

The science is, as tends to happen, rather more nuanced than stories of descent from famous dead people, and the documentary did a fine job of explaining why. Because you have two parents who have two parents, and so on, your number of ancestors doubles every generation. It doesn't take very long to end up with more potential ancestors than people who have ever lived. This means that a great many people share a great many ancestors. Your family tree grows rather more like a hedgerow the further you climb.

Since DNA gets re-shuffled every time a sperm and an egg are made, children don't always end up with equal amounts of genes from both parents. Stretch this over enough generations and you end up containing no DNA whatsoever from a number of ancestors. You are still family, you just don't contain any of their genes. These, to me, are mindboggling facts and much more interesting than sharing a handful of nucleotides with some old queen.

I especially enjoyed the section about Cymru DNA, shown on Welsh-language TV station S4C. This show and the ancestry company behind it, Cymru DNA Wales (owned by the controversial Britain's DNA), purported to link Welsh celebrities to spurious 'types' of DNA - for example, weather forecaster Sian Lloyd has a 'foraging' genome, while Plaid Cymru's former president, Dafydd Iwan, was sycophantically labelled 'ancient Welsh'. The representative from the show's production company hid behind the excuse of 'commercial sensitivity' to avoid discussing the details of the research.

Jobling made an important point here about how talking of 'quintessentially Welsh' genes is 'rank nationalism at work'. As Rutherford told us: 'DNA doesn't tend to reflect national boundaries.' Before broadcast, Sense About Science even felt the need to translate their genetic genealogy pamphlet (co-authored by Thomas and reported in BioNews 696) into Welsh in what I hope was not ultimately a futile attempt to stave off the further lightening of people's wallets.

Overall, I felt the programme had little new to offer the likes of me, but I'm the sort who spends his spare time writing about genetic astrology (see BioNews 696), why some of us are all a bit Viking and why a genetic geolocation test is nonsensical (see BioNews 753). If you've read anything about genetic ancestry and its controversies, you'll probably be familiar with most of the topics covered. Regardless, this documentary is an even-tempered discussion of the snake oil, the realities and the limits of shining a light into the fogs of history.