From Gordon Brown to Billy Bragg, George Alagiah to Trevor Phillips, every talking head in public life now itches to have their say about the nature of British and/or English identity. By and large, we're having a civilised chat over our ale or tea (or chai). Every sensible chap grasps that we refer to culture and values, not to ethnicity and certainly not (horror of horrors!) to "blood". The toxic pseudo-science of "race" surely died with the genocidal criminals who forged it. So it did. Yet here comes Oxford's professor of human genetics with the fruit of an utterly fascinating project aiming to establish who the folk we might label "old-stock" British and Irish really are. And what does he call his book? Blood of the Isles.
Don't panic. No need (unless you want to) to reach for a calming dram. Bryan Sykes's Blood of the Isles (Bantam, £17.99) sets out to supplant the "racial myths" and "virulent doctrines" - not to mention softer, scattier delusions - that formerly drove assumptions about ancestry with current genetic science. Originally a medical geneticist, Sykes wrote about the use of large-scale DNA sampling and matching to determine the origins and movement of human populations in Adam's Curse and The Seven Daughters of Eve. Among his triumphs was proof that Polynesians arrived in their archipelago not from the Americas but Asia. Sorry, Thor Heyerdahl: wasted journey. Now he and his team have travelled 80,000 miles and collected 10,000 samples to discover how the "clan" patterns of Europe play out in these isles.
The science, which involves tracing markers ("secret passengers") both in mitochondrial DNA passed down the maternal line and in the male Y-chromosome, is explained with an infectious zest. Sykes lightens research reports with snapshots of ancient history (and prehistory), with legends that clash or coincide with that history, and with a drizzle of droll anecdotes - from lecturing to an audience of one in Shetland to enjoying gourmet ice-creams in Lampeter. The only annoying tic comes in his repeated references to "we" or "us" when he means only long-settled groups in the isles. I'm not being PC: his book is so revealing that the new "we" as well as old should read it.
And what does it reveal? In essence, that the indigenous "we" are mostly Celts: "the genetic structure of the Isles is stubbornly Celtic" and, "On our maternal side, almost all of us are Celts". Of course, these so-called "Celts" come shrouded in foggy myths that Sykes debunks. Still, we need a term for a pre-Roman Briton speaking a Celtic language, and he retains it. The DNA record shows a surprisingly small addition of - inter-related - Danish, Saxon and Norman material. In the Viking or Saxon heartlands, north and east, this rises to 10 per cent or so; but not far beyond. The Celtic "bedrock" seems to have arrived in Neolithic times, sailing north along the Atlantic seaways; only a small minority crossed from central Europe. So this is a land not of Anglo-Saxon but of Iberian-Celtic attitudes.
Does this matter? Mostly, not a jot. Sykes's "genetic archaeology" leaves the task of ensuring mutual respect for all unchanged. But when a racist loudmouth - or, maybe, a bigoted French journalist - witters on about the "Anglo-Saxon" character of the British to bless or curse it, that fallacy should raise an even bigger laugh. As for the mantra about "a nation of immigrants" - true, except that many arrived thousands of years ago. And from a remarkable variety of places: Sykes identifies maternal "clans" in southern England deriving from sub-Saharan Africa, Syria and Jordan. Roman slaves, he presumes. But when it comes to "an African sequence from Stornaway in the Western Isles", he has "absolutely no explanation". At which point, perhaps, the human geneticist bows out and the novelist takes over.