If you want to be a genius, you must persuade your parents to become a dysfunctional family

Pity our parents. Step into a courtroom and you find that mum and dad have become a licence to kill ("sorry guv, but me dad ran off when I was four and mum loved the bottle more than me"). Step into the classroom and they're the reason for student failure (a short attention span is the "proven" consequence of a broken home). Everywhere else, from the boardroom to the bedroom, our parents are the extenuating circumstances that mould misfits and spawn the socially autistic. Could Monica be any different, given her mom? And what chance did James Archer ever have, with a dad like his?

Our psychological determinism is so deep-rooted that for years now we've accepted that dysfunctional families doom their offspring: if you looked back and remembered a raised voice or a broken plate, you could get away with bad-mouthing, mood swings, megalomania - everything was forgiven you and blamed on Them.

No more: a group of Canadian researchers at McGill University have lifted the burden of guilt from mums and dads everywhere. According to a study of more than 300 Americans, the most creative people come from families where parents are constantly at each other's throats.

The findings show that cross words across the kitchen table don't scar the little mites as much as inspire them. Dad's explosions of expletives and mum's banging of doors apparently prompt the progeny to dash off a symphony, paint a portrait, write a novel.

The McGill study is not only welcome as a tribute to youngsters' resilience, but as testament to the enduring mystery of our species. We have become ever more technologically sophisticated and scientifically literate, capable of explaining the origins of black holes and the benefits of sheep-cloning. Yet our understanding of human behaviour remains primitive: until the McGill researchers collected their latest evidence, psychologists taught that creativity sprang from calm, not chaos; and quarrelling parents were living proof of Larkin's famous line that "they fuck you up, your mum and dad", not a spur to Junior's self-realisation. (Some of us knew better all along, though. Like Joe Orton's homosexual lover, who murdered the playwright out of envy: "I should have been the genius," he claimed, "because I had a terrible childhood - my mother died when she swallowed a wasp.")

The McGill study warns us that psychology may be the most popular of sciences, but it is inexact, based on studies that are often contradictory and ultimately inconclusive. Moreover, by challenging what has become a domestic truism - all happy families are happy in the same way - the study blows the whistle on a science that adopts a Stalinist approach to our emotions, sacrificing the individual to the collective. To satisfy their theories, psychologists - amateur and professional - must blend our personal stories into one over-arching narrative. It's all very well to coin general terms - broken homes, dysfunctional families - to describe our particular roots. Yet one family's loud quarrels may prove cathartic for their children; another's, catastrophic. One couple's silence may bestow calm upon their offspring; another's, a sense of alienation.

Worse, the scientists of emotions allow us to excuse our present with our past. The labels they stick on us - healthy, unhealthy or downright psychopathic - are determined by our upbringing. Thus, ethical considerations such as "what is the right thing to do?" are drowned in a sense of inevitability: "I can't help my behaviour because my parents always screamed at each other." Shouldering responsibility gives way to passing the buck.

The Canadian study shows that psychology can get things wrong - not just in terms of shouting matches, but of fundamentals such as duty and accountability. Even the dysfunctional product of a broken home can see that that's not healthy.