After watching Ant & Dec’s DNA Journey on ITV, I can confidently say that one thing it failed to do for me – and which genetics could definitively answer – is clarify which one is Ant and which one is Dec. Alas, this mystery remains unsolved.
Aside from that, the documentary is entertaining enough. In the first episode, Ant and Dec travel around, talking to genealogists and distant relatives who have been identified by having similar bits of DNA to them – like Who Do You Think You Are? but with bonus genetics. We are introduced to Dixie Carter, who is described as a “genetic cousin” to Dec, though I couldn’t tell precisely what relation she is. The two shared an ancestor from around 150 years ago, and her presence provides light relief as she is a Texan wrestling promoter.
It is, of course, incumbent on science to spoil the fun. A common ancestor six generations into the past, like the one shared between Dixie and Dec, is one of 64 great-great-great-great-grandparents you have. Maybe Dixie was simply the most exciting relative the producers found. Without DNA analysis, the Geordie duo would not have traced her and other distant relatives, but the truth is that there is very little meaningful genetic relationship there.
Geneticists did not anticipate that the human genome would become such a saleable commodity. It’s estimated that more than 26m commercial genetic tests have been taken worldwide, mainly trading on the beguiling promise of revealing something about your ancestry.
The show is “sponsored” by the biggest of these companies, Ancestry, who are credible, and whose data – your data – is put to interesting use, such as producing scientific papers that analyse the genetic structure of modern Americans. Also in the programme were Alistair Moffat and Jim Wilson, founders of another, now defunct, company called BritainsDNA, which made headlines for some absurd and ahistorical claims over the years, including saying that it had traced the descendants of the Queen of Sheba (a Biblical character who may or may not have existed) and those of Eve, sticking with the Biblical theme. It was even behind claims that climate change would make ginger people extinct.
In 2012, Moffat threatened legal action against geneticists at UCL (to which I am affiliated) who had criticised some of the company’s claims. A paper in the peer-reviewed journal Genealogy documents this saga and the way BritainsDNA “made a number of dubious claims both directly to its customers and in the media”. Companies like that devalue the business of genetic genealogy, so it is troubling to see its key players – Moffat effectively introduces the show – feature so prominently in Ant and Dec’s show.
The marketing ploy of the genetics industry is to tell stories of belonging. This can be powerful because everyone craves autobiographical meaning. But the power of genetics to deliver narrative satisfaction is profoundly limited. All genetic genealogy companies play upon this to a certain extent. California-based 23andMe capitalised on the 2018 football World Cup finals with adverts suggesting you should “root for your roots” by “supporting the countries that reflect your unique DNA”, thus indicating that their marketing department clearly have no idea about football fandom.
Personal testimony on the Ancestry website has “Mark” discovering that instead of being 100% British, as he had always believed, he is “only 40% British, 25% German and 35% Greek”. Mark: it’s cool that you discovered you may have ancestry from Greece and Germany, though these results don’t and probably can’t tell you who those people were or how closely you are related to them. But regardless, you remain British, because that’s how citizenship works.
The maths of ancestry is a bit bewildering, but there are two steadying anchors. The first is that everyone has two parents. This means that the number of ancestors you have doubles every generation into the past. The second is that there are more people alive today than at any point in history. These two things may seem at odds: the number of ancestors you have goes up as we go back in time, but the number of people alive goes up as we go forward in time. The answer to this apparent conundrum is that we are all inbred.
Sooner or later the number of positions on our family tree are filled with the same people over and over, until at some point all the branches coalesce. Everybody now is descended from everybody then. For Europe, that time is about a thousand years ago. All people of long-standing European descent have the same ancestors a thousand years ago. What’s more, due to the way DNA is chopped up during the creation of sperm and egg cells, we lose genetic information from our actual ancestors, meaning that you have no DNA in common with half of your blood relatives from only three centuries ago.
Scientists are not in the business of telling you how to spend your hard-earned cash, but if you want to find out you have Irish, Scottish or even Viking ancestors, look in the mirror. If you want to find out you have royalty in your family tree, as I show in my book A Brief History of Everyone Who Ever Lived, you do. If you think these things matter, or reveal hidden secrets about your identity, there I cannot help. Family trees may be the ties that bind us, but those trees are pollarded. Most of your ancestry is lost and can never be recovered, not with historical certificates or DNA, despite its many explanatory powers. You, me, Ant and/or Dec — we are all descended from multitudes.
• Adam Rutherford is a geneticist and author
