Barbara Keating lives in Ireland and her sister Stephanie in France. Their separate lives infuse the drama of their début novel. Rosita Boland reports.

They say two heads are better than one, but in the solitary pursuit of writing fiction, joint efforts are unusual. Sisters Barbara and Stephanie Keating have an extra complication: one lives in Ireland, the other in France.

"We had always written things together as children," Barbara says. "Since we live in different countries now, we wanted to do something together, and we were thinking of a few different things."

"Then I received a fictional letter from Barbara in the post one day in France," Stephanie recalls, "with a brisk note attached, asking me what was my response to it." The letter Barbara had written was to be the beginning of the novel. Three weeks later, Stephanie sent a reply and thus the exchange of letters, faxes and e-mails began, which would result three years later in the novel, To My Daughter in France. . .

"It's not a literary effort," Stephanie correctly points out, to the agreement of her sister. "I wouldn't be upset if it was described as a page-turner." One does not usually associate Harvill Press with "page-turners". But this is an honest assessment of their collaboration, since the writing is workmanlike, with entire passages reading as one long self-indulgent cliché, through which the reader flounders.

To My Daughter in France. . . is set between Ireland and France, during the periods of the second World War and the 1970s. Stephanie wrote most of the chapters which are set in France: the converted mill she lives in Languedoc overlooks vineyards, which play a central role in the novel. Barbara, who lives in Kilternan, Co Dublin, did most of the research, intrigued by stories she had heard from her mother about living in wartime France, which led them to choose that period.

"I wanted to write about the war years, so one set of dates led to the other, the 1970s," Barbara says. The book's heroine was born in the 1940s, and the narrative then jumps to her adulthood in the 1970s. The title character is Solange de Valnay, the illegitimate daughter of Irishman Richard Kirwan, conceived when he was recovering from wounds in wartime France. Richard is already married, with a family back in Ireland to whom he returns after the war, and Solange's existence is only discovered after his death, when she is mentioned in her father's will. The Irish family members are, as one would imagine, displeased.

The rest of the book uncovers Solange's story and tracks the impact of the discovery on the rest of the family: Helena, the wife in Ireland, and her three children, Eleanor, James and Elizabeth. Solange must also come to terms with the reality of having a different father, and with her new and substantial wealth.

The weakness in writing a collaborative book is unfortunately demonstrated in the unwieldy and rambling structure. Each sister wrote a bit, and then the other picked up where she had left off; there was no plan.

"We'd write about 15 chapters and then meet to discuss what we'd written, but we didn't discuss in any detail what we'd do next," says Stephanie.

"We didn't really know where it was going," says Barbara cheerfully. "To the last page, there were surprises for us both."

What's interesting about the novel is the authors' approach to the subject, namely, the evergreen and complex topic of love. For modern fiction, love in this book is given a curiously old-fashioned treatment. Women suffer, mostly in silence and uncomplainingly, for the sake of love. Their men, however, get away with azure-blue murder and are admired for it. Teeth and edge come to mind.

So how would the sisters themselves define love, of which they focus on so closely in this novel?

"It's primarily about giving. It goes wrong when one person takes but doesn't give," muses Barbara. "It's about generosity," adds Stephanie. "Generosity in a long-term relationship is very important. And laughter. You need to have a huge amount of determination for love to survive."

Given the difference in the way their male and female characters are represented, do they think love means something different to each of the sexes? "Yes, I do," Stephanie says. "Women are more able to give absolutely everything. Even today, they can do that; give with no strings attached and no conditions attached. I'm not sure that men can love unconditionally."

"Women perhaps love in a more nurturing way," Barbara reflects. "They are willing to toil and dig away. Men love in a more providing way. They really are the hunter-gatherers. Although I don't think that's the case for our children's generation. I think a lot of attitudes to women were very different back then. A lot of women did suffer in silence. They were expected to get on with it, regardless of how they felt."

The novel is dedicated to the authors' husbands. Sadly, Barbara's spouse never saw the published book: retired Judge Rory O'Hanlon died earlier this year.

The sisters are a quarter of the way through their next novel, which follows the lives of three young women in a newly independent Kenya in the 1960s, where the Keatings grew up.

To My Daughter in France . . . by Barbara and Stephanie Keating, is published by Harvill Press at £16.99 in the UK.