http://www.guardian.co.uk/commentisfree/story/0,,1941852,00.html

Genealogy is like PlayStationing - you think it's just special-interest fun for people who don't do friends, then you look round and everybody's at it. There are 3 million people trying to find their ancestors through the national archives.

The archives are, of course, the internet face of the Public Record Office, which in the days before the wonderweb was like any other public library, without the children - rammed to the gills with old people. I did not pick up the idea that family-treeing was an elderly pursuit, like embroidery and complaining, off the telly, but prima facie from working in the Public Record Office at Kew (since you ask, I was researching black history in Lewisham). I never saw anyone under 60. Well, genealogy is not a young person's game. By definition, it lacks high drama - if anyone in your family had ever done anything remotely interesting, nobody else in the family would have stopped talking about it.

In all probability, it lacks context - sure, you might find a tinker uncle who went to a Putney debate or was a Chartist, but generally speaking they all just get born, marry and die. With shaming prejudice, I imagined this was why young people weren't interested. We were too engaged with the world, too fresh and full of vim, too iconoclastic in spirit and broad in intellectual scope to care what our personal history held.

In fact, though, the alienating factor for the younger generation was simply the opening hours. With records available over the internet since 2003, the surge in interest is far more extreme than can be accounted for by an ageing population. If this were an interest of a fixed demographic, you could just leave it be, much as there is no need to pick fault with teenage girls and their stationery fixation, or middle-aged men and their funny sports.

But if this is going to be a nationwide, cross-generational thing, can we take a moment to reflect on how utterly pointless and self-regarding it is? I called this a branch of history, but in fact scraping round for ye olde DNA is the very opposite of history. Historical inquiry would always direct you to the heart of events, whether in the traditional sense (royals) or the revisionist one (radicals, grassroots movements, that sort of thing). From neither perspective can the criterion "they've got to be related to me before I'm at all interested" be anything but an impediment.

A genealogist speaking to the Times at the weekend commented: "It is not just about collecting names. It is about understanding who you are, and how you came to be who you are today. It is about knowing yourself." Superficially that doesn't mean much - in the furthest reaches of the nature/nurture debate, nobody has ever suggested one's distant second cousin could be anything more than a curiosity. And yet that tells you all you need to know about the kind of person who family-trees for a hobby - who thinks that's time well spent, getting to "know yourself, understand who you are". If therapy is for people with more money than sense, genealogy is for those with more time than either.

It conveys a silent prejudice that never has the guts to announce itself. Ferreting about for antecedents in parish records says, effectively: "I attach a certain value to having always come from Suffolk or wherever. Oh, no, no, no, I don't mean being foreign is bad, I just mean it's so much nicer not to be."

Worse is the tacit snob-lottery: everyone secretly hoping they'll find a great-great-great aunt who nobbed a royal - out of wedlock so much the better, since they can show off about it that much more, with the slut value giving a chimera of self-deprecation. It's a horrible business. It's like porn involving animals: just because it's on the internet doesn't mean it's OK to look at it.

zoe_williams@ntlworld.com