Shakespeare in Love, Schindler's List, The English Patient, Onegin - all extraordinary films with a connection to an extraordinary family: that of Jini Fiennes. Actors Ralph and Joseph and director Sophie pay tribute to the house their mother built

Towards the end of her life, the writer Jennifer Lash made the ancient pilgrimage to Santiago de Compostela in the north west of Spain. Lash was in remission from breast cancer, and she felt she had much to be thankful for. When she reached the Shrine of Rocamadour in the south of France, she walked to the rim of a valley famed for its echo, and impelled by a sense of holiness in the hot stones, called out the names of her seven children: "It felt," she wrote, "as if those names sped into the midnight rocks, and would remain there, in some way, to guide the named."

For Lash, her children were her best prayer. When she died in 1993, her children felt bereft, but not abandoned: "Jini is vividly present to all of us," says her eldest son, the actor Ralph Fiennes, who dedicated the Oscar he won for his role in Schindler's List to his mother's memory. [My note: he never got an Oscar] Later, on the set of The English Patient, Fiennes arranged a more lasting memorial. The publisher Liz Calder had made the trip to the Tunisian desert to oversee the adaptation of Michael Ondaatje's novel. Fiennes seized the opportunity, between takes, to pitch his mother's last novel, unpublished in her lifetime, to Calder. When Blood Ties was duly published by Calder's company, it felt, says Fiennes, "like a kind of completion."

Blood Ties, written while Lash was battling the breast cancer which eventually killed her, is a story of darkness, damage and, ultimately, redemption in a fractured Anglo-Irish family. It is an inspirational book and attracted a strong following among readers who write to the Fiennes family from all over the world to tell Jini's children what the book meant to them. Last year, Bloomsbury brought out On Pilgrimage, Lash's account of her journey to Santiago de Compostela. With both books now out in the US, three of the Fiennes children, Ralph, his brother Joseph, star of Shakespeare in Love, and their sister Sophie, and independent film-maker, are much involved in publicising Jini's work.

There is no great physical resemblance between the brothers and sister: Ralph has an almost unsettling quality of stillness, Joseph is quick and whippy, while Sophie, tall and grave, resembles the published pictu-res of her mother. In their manner, though, and in the way they finish each other's sentences, there is the kind of settled complicity that only siblings share.

All three are immensely proud of their mother's literary achievements, and Blood Ties, set on the south-west coast of Ireland, where they did most of their growing up, has a special resonance for the family.

Jennifer Lash first came to Ireland in 1971 with her husband Mark Fiennes, a photographer, on an assignment to record the ways of Irish country life. Jini, who had suffered a breakdown after a miserable upbringing in Surrey and saw England as "a sad and difficult place", considered the wild shores of west Cork the ideal place for her own family to grow up. Joe, the youngest, was only four when they made the move.

"Jini was a great propagandist for Ireland," he remembers. "She and my father had no easy means of making a living there, but they both wanted to get away from the rat race of 1970s' England. My father built our house with his own hands and the whole thing was a huge adventure." Jini was excited to bring us up in this incredibly free and abandoned landscape," recalls Sophie. "She was a Jungian who wanted to expose us to the real, root nature of life. She loved the idea that the archetypes you see in myth and fairy stories were still alive and kicking in Ireland."

Blood Ties centres on the education of Spencer, an unloved child foisted on strangers. As well as bringing up their own six children, Jini and Mark Fiennes fostered a boy, Mick, from the age of 11 after reading about his plight in a local newspaper. "Jini was a gifted child psychologist," says Ralph. "She would probably say that she wasn't writing about anyone in real life. But I think we can all see that the experience of bringing up Mick, who had only ever known rejection, giving him security and watching him flourish is the raw material for the novel. Mick [Michael Emery] is now an archaeologist and a brilliant historian."

All the Fiennes children have done well. Apart from Ralph, Joe and Sophie, there is Magnus, a composer, Jacob, a gamekeeper and Martha, a film director. Creativity, Jini's children recall, was always a premium in the family home. "I don't remember being pushed in a certain direction, but I do remember being surroun-ded by stimulus all the time," says Joe.

"It wasn't that she wanted to hothouse us," says Sophie. "It's just that she was genuinely excited by things. She wanted to go and see Waiting for Godot, so she took me along. I was nine. But I was comple-tely fired up for it just by being with Jini."

Blood Ties was Jennifer Lash's sixth novel, written like the others, in moments snatched from the chaos of family life. "We were all aware of how important it was for her to have time and a room of her own to write in," says Ralph, while for Joseph it always felt like "a kind of collaboration. Jini shut her door when she went to write, but she didn't shut us off. She made us party to the process of writing and I always felt, even though we were just kids, that we were participants in her work."

Buried in domestic rubble, however, Lash had little chance of courting fame in her lifetime. "Despite having had two novels published, she didn't feel there was a publishing world waiting to embrace her," says Sophie. "She had no access to the world of networking and promotion and I know she felt frustrated and undermined."

For the Fiennes children and their father the posthumous success of Jennifer Lash is not without its irony, but they are in no doubt that it is what Jini would have wanted. Their own part in midwifing their mother's book through the publictiy process is down-played. "It is," concludes Ralph, speaking for them all, "a way of giving back something to someone who gave everything."