Sermons are not the stuff of popular fiction. Some exhortation to the virtuous life, delivered from polished wood eyrie? No recipe for a best-seller, surely. But for a US novelist whose first novel was a surprise hit, whose subsequent work featured in the notorious but sure-fire Oprah Winfrey book club slot, the Protestant Sunday sermon underlines and informs both her work and the influences of her life.

"I think it is a sense of the structure, of the need to relate something deeper back to an everyday occurrence . . . first you tell the parable and then you go back to what was cooking for dinner," says Sue Miller, wrapping her cardigan around her in a Dublin hotel.

Miller's new novel, her seventh, is The World Below. Her first (published) was The Good Mother, in 1986. In between have been a number of books revolving around personal situations, family tensions, love affairs. "I am seen as a domestic realist," she says, with just a trace of irony. There is a depth to her writing, an accuracy of report.

Nobody else in her Midwestern family of churchmen and academics was a writer. Her father was a church historian, and it is from this the development into novelist came. Further back, the lineage was of solid Presbyterian and Congregationalist ministers. She can see that influence in her work, but it is possible that the intimate content of her books, particularly the unabashed sexuality of the central females, would have embarrassed, if not shocked them. Anyway, she was safely distant from the home influences from her late teens, when she moved to Boston to attend college, then married and had her only child. Divorce came soon, before her son was four. Years later she married again, to fellow novelist Douglas Bauer (The Very Air). They have also parted but remain friends.

She has taught writing programmes for a number of years. Before that, early on, she was a day-care worker at a pioneering workplace crΦche for a shoe factory, starting in the late 1960s. This proved to be valuable background for her later novels. "People talk to you at the day care centre, so I was hearing about a lot of marriages. Leaving or collecting the kids, people would tell you about fights they were having with their spouses, and all sorts of things." This curly-haired woman with her pleasant, slightly shy manner, must have been a natural sympathetic ear.

"Divorce is incredibly difficult for children. I didn't realise how hard it would be for my son," she says. This difficulty is reflected in most of her novels, as are many of the situations in which she found herself.

In the books there is often a scene in which one character - the loathsome Justice of the Peace Brower in The Good Mother, for example - ticks off the divorcing parent, telling them that marriage is for life, and difficulties have to be worked through. That sounds very recently familiar in an Irish situation, but Miller says she has not had such a personal reaction to her own two divorces, although the daycare centre, not to mention subsequent life, provided a wide range of experience.

"There is a sense we have of some mythic past where everyone stayed married forever. But other factors were ending marriages then. Maternal mortality rates were so high . . . Children were often brought up by someone other than their mother. One of my forebears, a sober clergyman, had three wives because they, unfortunately just kept on dying."

Against this background then (which is a big part of The World Below), it was seen by the crossover generation as "damnably frivolous", she says, "to end a marriage voluntarily, with death ever present threatening to do the job for you".

The 1940s and 1950s were perhaps the free zone between the bad old days and the modern world, where antibiotics and good post-natal care changed life expectancies. "But, of course, even then it wasn't always so good."

The World Below is the story of a fifty-something divorcee living in San Francisco who inherits her grandmother's house on the east coast. When she returns to it, she discovers diaries which fill in some missing pieces in the jigsaw of her grandmother's life, to surprising effect. The idea might not be particularly new, but the writing is well-crafted and the characters real. The motif which, ambiguously, gives the novel its title is a lost community in western Massachusetts, a town flooded by a dam, which can be glimpsed beneath the surface of a lake when conditions are right. "I was dealing with the notion of home as a safe place in the world, a feeling that it is now lost to us - maybe in America more than other places. The world as I knew it has changed so rapidly . . . the world in which I grew up seems very gone to me - it's sad," says Miller.

She has a fixed writing routine, and manages about three hours a day. She also edits an annual anthology of American short stories, and has written a memoir of her father, who died of Alzheimer's 10 years ago.

Her books have an even tone, whether describing the pretty dΘcor of a whitewashed New England holiday house or passionate sex between a divorcee and the lover she sees once a decade. "I don't think I feel censorious about any human behaviour. I suppose one of the themes of my books is that there is no such thing as perfection in relationships, and how people come to accept that, or not."

Her son Ben, 33, now lives in Africa. He works as an anthropologist, and runs study programmes for college students. "I didn't write much when he was growing up . . . as a single mother I didn't have the time. But I did write one novel, still unpublished, in my 20s, and one just before The Good Mother.

"With The Good Mother I was very conscious of having to tell a story, to engage the reader with the plot. I thought I was writing a serious book that would sell 15,000 to 20,000 copies, so it was amazing to me to have it taken as it was" - some sort of potboiler, apparently.

Her sixth novel, While You Were Gone, was an Oprah Winfrey book club selection, the ticket to fame and fortune for many a novelist. Recently the Oprah designation was subject of controversy when Jonathan Franzen, the self-proclaimed great US novelist of the chunky and enjoyable The Corrections, refused to allow his tome be nominated by Oprah. His reason was, apparently, that this made it too populist a book, whereas he seemed to think it belonged with Melville and Conrad. (In fact, his style is very similar to Sue Miller, with some humour added. That is not to denigrate; both are exceptionally readable and enjoyable.)

Miller thinks Franzen's spitting-the-soother reflected a gender division in literature, especially in the US. An Oprah book will be mostly bought and read by women, because it is mostly (not entirely) women who watch and idolise Oprah. And "there is a thing that if too many women are reading your book it can't be art. High art fiction is written by men, for men," she says.

"Having my first book be such a commercial success means my writing has been dismissed in certain circles."

Reflecting on this unfortunate situation brought to mind a magazine report of the filming of the recent television adaptation of Crime and Punishment, with actor John Simm as Raskolnikov. The magazine journalist who went to St Petersburg to see some of the location shooting was struck by how many of the ordinary citizens had read Crime and Punishment, even carrying tatty copies around to compare what the film crew was doing with what Dostoyevsky had written. People whose reading would be a quick scan of the Sun in Britain, he reported, were familiar, and passionate, about the work of their genius. There was no class divide on reading material.

Oh, those Russians.

The World Below is published by Bloomsbury at £10 stg