Lucky charm?

The literary establishment persistently ignores the novelist Jodi Picoult. Now film critics have panned the movie version of My Sister's Keeper. Nevertheless, readers love her.

Heather Wahlquist as Aunt Kelly, Abigail Breslin as Anna and Cameron Diaz as Sara in My Sister's Keeper, which critics have not been kind to.

Reviews of the film of Jodi Picoult's bestselling novel My Sister's Keeper - about two sisters, one with leukaemia, the other raised to be her bone marrow donor - haven't been kind.

"There is always a fine line between moving and manipulation in telling heartbreaking stories," noted Betsy Sharkey in the Los Angeles Times, "and it is here that [the director] Nick Cassavetes largely fails us." Most of the time, authors defend movie adaptations of their books even if they dislike them. The accompanying sales fillip can be huge, so it benefits them to remain on message and give the impression that the film has their blessing. That Picoult feels no such obligation tells you a lot about how successful and confident she is. She has griped about the film of My Sister's Keeper, which stars Cameron Diaz, to interviewers ("My solace is knowing people can still pick the book up...") and her website carries a fascinating "apology" to fans: "Yes, I know the ending is different. Yes, I know some of you are very upset. I didn't change it. The author has no control over the movie, and it was hard for me to accept too. However, there's a great deal in the movie that I think is great, and I enjoyed watching it - and I hope you did too. Please don't e-mail me asking me why I changed the ending, or 'let' Hollywood do that - it wasn't something I had any control over."

The coup de grace is a supplied e-mail address for fans to use to send complaints to the film's maker, Warner Bros. So who is Picoult, and why is she so powerful? The first question, at least, is easy to answer. The 43-year-old American has sold more than 16 million novels worldwide. She lives in rural New Hampshire in a colonial-style house set amid 11 acres of land. She has three teenage children and is married to Tim Van Leer, an antiques dealer whom she met while coxing a men's rowing crew at Princeton University, where she studied creative writing.

Her mother was a nursery school director, her father a securities analyst on Wall Street. She keeps animals (geese, chickens, ducks, two donkeys) and, when she's writing, a strict routine: her day starts at 5.30am with a three-mile hike; she's at her desk in her attic study by 7.30. Typically, her attention will be divided among three novels: the one that has just come out, which needs promoting; the one that's just about to come out, which needs proofreading, and the one she's writing, which needs researching.

"Writing is total grunt work," she has said, stressing the importance of sitting down every day and writing something, even if it is later struck out: "You can always edit something bad. You can't edit something blank." Picoult's success is all the more remarkable because she has achieved it with a genre of her own invention - what the New York Times has called "children-in-peril" fiction - rather than by choosing to write thrillers, say, or chick lit. Her first novel, published in 1991 when she was in her mid-twenties, was Songs of the Humpback Whale, about a woman who leaves her abusive, distant husband, taking their 15-year-old daughter with her, only for the husband to track them down. Since then, each novel has focused on an emotive, zeitgeisty subject such as date rape (The Tenth Circle), teen suicide (The Pact), high school shootings (Nineteen Minutes) or child abuse (Perfect Match). Around this central scenario Picoult will weave a compelling but largely humourless fable, usually narrated by several key characters in alternating chapters. She can be florid but is nevertheless easy to read and digest.

Picoult admits to being a practitioner of "McFiction" designed to be read a chapter at a time, perhaps during a lunch break or before bed. At the same time, she makes extravagant claims for her books, telling one journalist: "When I think about writers who use fiction as social commentary and to raise social awareness but who are also very popular, I think of Dickens." On one level, this is fair comment. But Dickens was taken seriously as a journalist and tastemaker even if his novels were sometimes indifferently received. The contemporary literary establishment has persistently ignored Picoult. There's a suggestion that her interest in familial dysfunction and sick children panders to base instincts; that the best place for her novels is on supermarket shelves next to the non-fictional "misery memoirs" they resemble in content. Picoult is rarely reviewed in broadsheet newspapers, and when she is the results tend not to be glowing. But this doesn't bother her. She knows her novels are what the trade calls "review-proof": their success depends on word of mouth recommendation, big marketing campaigns and her willingness to criss-cross the world on lengthy promotional tours.

An important factor in Picoult's success has been the renaissance over the past 10 years of the book club - a trend tapped into most famously by Oprah Winfrey and later by the UK daytime television presenters Richard Madeley and Judy Finnigan. (Picoult's British sales were nothing special before the duo - or rather Amanda Ross, the managing director of Cactus TV, which made their show - chose My Sister's Keeper for their book club in 2005.)

Picoult's books are archetypal "book club novels" in the sense that they exist to be discussed. There's nothing new in this. The years following the Second World War were a golden age for book clubs in the UK. Postal book-of-the-month clubs such as the Book Society and the Book Guild were booming and every town had a Boots Booklovers' Library. The books that did best reflected very precisely the concerns of the women - and they were nearly always women - who bought or borrowed them: class, family, houses and of course the "servant problem" of the working classes preferring to work in factories than as cooks or scullery maids.

Writers we still remember who have book clubs to thank for their fame include Nancy Mitford, Daphne du Maurier and Angela Thirkell. In the 1945 film Brief Encounter, the heroine Laura Jesson has just been to Boots to change her books when she meets the dishy doctor Alec Harvey on the station platform. As the academic Nicola Humble points out in her book The Feminine Middlebrow Novel: 1920s to 1950s, book clubs ensured that "large numbers of people read the same books. This also guaranteed that this literature became a talking point, a shared cultural reference against which their largely middle-class female readers could define themselves."

For the most part, Picoult's readership comprises middle-class women who want novels that reflect their anxieties in an age of 24-hour news filled with health scares and apparently random violence; novels they can discuss with friends, either in person or online; novels that put them in control and make them feel, briefly, like experts. (To this end, Picoult takes her research extremely seriously. For Handle With Care, in which a New England couple have a daughter with osteogenesis imperfecta, a rare bone disorder, she didn't just read extensively, she spent time on hospital wards with specialists.)

Picoult's books prey on the idea that when disaster strikes it will be from an unlikely quarter. You may have thought you were a good, responsible parent, doing your best. But you were wrong - and look: your son has just shot a bunch of his classmates. Literary novelists have colonised this territory too, most notably Lionel Shriver, whose We Need to Talk About Kevin, a riff on the distinctly Picoult-ish theme of bad-seed children, enjoyed critical acclaim as well as huge sales. DBC Pierre and Douglas Coupland have both incorporated high school shootings into their books but they didn't get called cynical and opportunistic. Nor, you imagine, did they follow their novels by attending conferences devoted to ending violence in high schools as Picoult has done since the success of Nineteen Minutes. (She feels passionately about the subject, telling one journalist: "This is a topic we need to start talking about. We can go on not talking about it, but a lot of kids are going to die.")

For all her success, Picoult isn't aloof. She doesn't have the time to be. As she has said: "It's a fallacy that writers have to shut themselves up in their ivory towers to write. I have all these interruptions, three of which I gave birth to." She has also experienced her fair share of the kind of medical trauma that fills her books: her son Jake, aged five, developed a benign ear tumour that could have killed him if left unchecked. Picoult and her husband pursued an experimental treatment that involved 10 operations in three years. But it was successful, and Jake can now hear.

Picoult's next novel will be about a boy with Asperger's syndrome who becomes obsessed with crime scenes - so obsessed that he ends up a murder suspect. (You can't deny the brilliance of this idea.) She has said that, for her, her books represent a kind of magical thinking: she puts herself through the emotional wringer while she writes them in the hope of conferring a degree of immunity on her family.

You can't help wondering if that isn't why so many people love them. They're word amulets - lucky charms for keeping the darkness of the modern world at bay. And nothing any critic has to say will lessen their potency.