An anthropologist of the future wanting to study the life of British children in the early 21st century would have a field day with Outnumbered, the sitcom beloved of the middle classes because it so precisely seems to reflect their lives.

In the opening episode of the fourth series, shown on Friday, daughter Karen is having a conversation with her mother, Sue, who has just started to work full-time. "It's a mum's duty to pick up her children from school," she opines.

When her mother points out that she herself might like to work when she grows up, her retort is swift: "See, you're getting aggressive. That's what happens to women who work like men. They start turning into men. They get hairy chests and they smash up town centres." Sue exclaims in exasperation, but Karen barely looks up from her colouring. "You're getting aggressive. You'll get hairy." As a mother who works full time and spends a lot of the rest of my life sitting around kitchen tables having remarkably similar chats with my offspring, the exchange made me rock both with laughter and recognition. It is this sense of shared experience that has made Outnumbered, written by Andy Hamilton and Guy Jenkin, but also partly improvised by its cast, such a success.

Whereas most television sitcoms, such as My Family, which preceded it on screen last week, rely on incident, plot and comic misunderstanding to raise a laugh, Outnumbered is always at its best when its characters are simply bumbling through the mundane business of their lives: the fight over the Wii controller, the cheese stuck in the toaster, the dinosaur melted in the microwave, the keys which vanish just as you are leaving home.

It is particularly sharp on the vagaries of modern language: this week's conversations about the use of the word "gay" could have been recorded in many homes as a generation of school children apply it in the new sense of "feeble" to the horror of their parents who have co-opted it (against the wishes of a previous generation) to mean homosexual. The glee of the children when their father described the Wii controller as a "nunchuck" - "you said you'd never say that, you said that it wasn't a real word" - was equally astute.

From the anthropological point of view, however, it is the way in which the children behave that is of most interest. The family depicted in Outnumbered is one where the children rule: their parents are hapless, helpless adjuncts to the kids' power. It is not only that the youngsters argue each and every point. It is that on many occasions - such as Karen's decision to attend her uncle's funeral - they get their own way against the wishes of their parents.

In this way, Outnumbered depicts the sea change in behaviour in which a generation brought up to be submissive to its parents, finds itself once again in thrall - but this time to its children. For all its humour, it is essentially true.

Now back for its fourth series, the main question concerning Outnumbered is, 'Is it still funny after all this time?' The answer would appear to be 'Yes' - mind you, the fact that the first episode went out after My Family probably helped.

Eldest son Jake (Tyger Drew-Honey) is getting into a stage of typical teenage stroppiness, rallying against other members of the family and their attitudes, such as his mother Sue's (Claire Skinner) views of gay stereotypes; troublesome Ben (Daniel Roche) is refusing to wear his Wii safety cord and is under the belief that Jeremy Clarkson is gay; and curious Karen (Ramona Marquez) has an idea for stopping people stealing mobile phones by using bubonic plague.

The parents also have their own trouble, with father Pete (Hugh Dennis) quitting his job as a history teacher over a point of principle (and seemingly his own stupidity) and now working as a supply teacher, meaning Sue is working full time - and Karen is not happy about that. Pete is also having trouble with a eulogy at the funeral of his late gay uncle, which Sue finds amousing.

Outnumbered is still one of the best sitcoms around as far as I'm concerned. The semi-improvisation with the children is a joy to watch, especially when it comes to Karen. Let's hope it continues to keep the pace up.

Outnumbered - review

The family in Outnumbered make me want to shout at the telly, says Sam Wollaston.

Outnumbered, Friday 9pm, BBC One

Although there have been funnier and cleverer British sitcoms, there's no denying the uniqueness of BBC One's Outnumbered. When it arrived on screens back in 2007, we'd seen stressed-out parents and troublesome children in comedies before, but kids who spoke in that wheedling tone, argued like they really meant it and came out with strings of bafflingly logical questions - which is to say actually behaved like real kids? Totally new.

Outnumbered, Series four, BBC One

Outnumbered amusingly brings home the fact that parents spend a large chunk of their lives shouting the word "no" until it seems to be the only one they ever use.

'Outnumbered': the return of a Noughty pleasure

The BBC TV comedy that encapsulates the family angst of a generation of overstretched, bewildered middle-class parents makes a welcome return.

Outnumbered: Not the run-of-the-mill family sitcom

Four series in, Outnumbered has gained popularity and the seat-of-the-pants style still works as well as it did back in 2007.

The show that's given family sitcoms a good name returns for a fourth series. Tonight's plot centres on a family funeral and Pete losing his teaching job after resigning on a point of principle. Not that any ongoing story is necessarily what keeps you watching here. No, it's the details that make you squirm in recognition, as when Pete's mother ("I lack the warmth thing") suddenly remembers one of her klutzy son's childhood nicknames: "Cack hands!"

As My Family comes to an end, Outnumbered picks up the domestic sitcom baton and hits a home run.

Another year has passed but Karen and Ben are still able to exasperate their parents and their older brother Jake with their realistically surreal childish logic.

Enjoy it while it lasts.

Tonight the family are off to a funeral. It's Pete's duty to perform the eulogy for his Uncle Bob but the kids are determined not to miss out on this chance for what they see as a party.

As Pete and Sue try to avoid upsetting Karen by explaining to her that a funeral is a happy occasion, they end up settling on "sad, with a strong element of celebration".

But Ben isn't worried. He's been to a cremation before - or at least he thinks he has.

It proves to be the unlikely subject for one of the best jokes in a lovely episode that also contains a special gag just for Jeremy Clarkson.

Weird, isn't it, that on the same night that My Family, BBC1's old-style sitcom about the comic domestic trials of the middle-class Harper family, quietly shuffles off TV's mortal coil the new series of Outnumbered, BBC1's semi-improvisational and much more realistic domestic comedy about the middle-class Brockman family, starts a new series.

Over the previous three series the show's young stars have honed their adult-baiting antics to perfection, while the weary, defeated or bemused expressions on the faces of Claire Skinner and Hugh Dennis ring ever more true. The family are attending Uncle Bob's funeral in this episode. "The important thing to remember is that it's not a sad day," Sue tries to tell Karen, who very reasonably retorts, "Well, it is for Uncle Bob." Ben, meanwhile, insists he's been to a cremation before - except Pete points out that it was actually a hog roast. Not surprisingly, the vicar (John Sessions) wishes they'd never come.