Interview: Leila Aboulela, author

But the deeply personal story at the novel's core is based on the real-life romance between one of Aboulela's favourite aunts and her childhood sweetheart, Hassan Awad Aboulela.

He was a celebrated poet who wrote the lyrics for many popular Sudanese songs. Tipped to take over the thriving family business, he was paralysed in a freak swimming accident and in the blink of an eye the young man's dreams and the family's plans for his glittering future were snatched out of reach.

Called Nur in the novel, the poet is the second of two grown sons of patriarch Mahmoud Abuzeid by his first wife, Hajjah Waheeba. Abuzeid is also married to a worldly Egyptian, Nabilah, with whom he has two more children. Abuzeid runs a business empire with his brother Idris, whose middle daughter is married to her cousin, Nassir. Idris's youngest daughter, Soraya, is betrothed to Nur.

Persistent snow kept me off the trains, so I talked to Aboulela by phone to Dundee, where she's finally arrived after an epic journey from her home in Qatar, including ten hours' delay at Heathrow. I have cause to curse the weather for preventing a meeting, for she exudes warmth and intelligence, and I can actually hear it when she smiles.

Hassan Awad Aboulela died in 1962, two years before Aboulela was born, but her father spoke of his cousin often. "Cousins were very close at that time in Sudan, in general, and they all grew up together in one hoash, which is best described as a family compound where they had easy access to one other. My father had five sisters and four brothers. He had three uncles and each of these uncles had similar numbers of cousins.

"That's huge numbers of people you are very close to, and very intimate with. Hassan, who inspired the book, was close to my father in spite of their age gap. When Hassan went to study in Alexandria, in Egypt, he went with my father's older brother, and my father followed after. Their lives were very similar until Hassan had the accident. It was a shock to the family. That part is true, not fictionalised. The nucleus of the novel is true, the Hassan/Soraya story, plus Hassan's career. The other characters and the set-up, such as the polygamy, with the two wives, all that is imaginary."

Affection was one of her inspirations, says Aboulela. "I knew Hassan's sweetheart, my aunt - who shall remain anonymous - very well. I am close to her and always had this idea that she had this romantic past, this broken engagement. The other thing was that my father's family were very much as described in the novel, business-oriented, traders, into money. They were not into literature and art, so when I started to write, that was very surprising, since I'd trained as a statistician."

Aboulela grew up in Khartoum. She was educated at an American school there, and grew up reading books that are familiar to us, but would have been exotic to most Sudanese children, such as Little House on the Prairie, Little Women, Harriet the Spy and A Wrinkle in Time. She graduated from the University of Khartoum - the only woman in her statistics honour class - and came to London to study at the LSE. Nothing in those studies prepared her for an author's life, she says: "We didn't really write essays on the statistics course."

Then in 1992 she found herself in Aberdeen, alone with two small children while her husband worked on the rigs. Writing fiction provided a much-needed outlet. Her two novels, The Translator and Minaret, were longlisted for the Orange and IMPAC prizes, and the former was also shortlisted for the Saltire Scottish Book of the Year Award. In 2000, Aboulela won the first Caine Prize for African Writing for her short story The Museum.

Whenever literature is mentioned - and thematically, a love of books is integral for both Nur and Soraya - that smile I mentioned beams down the line. "I wasn't trained to write non-fiction," she says. "For fiction, I went to a public workshop, but I mostly learned through reading. I read a lot of fiction."

And it's clear from the dexterity with which she handles her story that she's learned those lessons well. Using multiple narrators and moving the action between Sudan, Egypt, and the UK, Aboulela picks out the contrasts and conflicts at play in Sudan at the time, conflicts that to some extent are still being fought within Islam today.

Reading Lyrics Alley, I was struck by the claustrophobic environment. Extended families living together, working together, marrying one another - it's a very closed world.

"It's not like that any more," she says, explaining that economics have forced many to leave their extended families to find work. Plus, it's more common to marry outside the family. "My father married out of the family. I also married outside the family. But I did grow up watching my cousins, whose parents were cousins, and as you were saying, there is this claustrophobia. Sometimes I saw it as narrow, and sometimes I was envious of it, because it's so safe and comforting and everybody is loved so much and there are no challenges, no cultural clashes. That can be very comforting."

Isn't there a danger of growing suspicious of anything deemed "other", which can lead to hostilities? "Oh definitely! My mom struggled a lot with this feeling that she's an outsider and her children - me, my brother - are not good enough. I grew up in this atmosphere. It is, I agree, very limited. It's almost disabling because you are not really challenging yourself. You're in a comfort zone."

The book's outsider, the Egyptian second wife Nabilah, is a complicated character. Superficially, with her modern ideas and refusal to be sidelined, she seems like the woman western readers would best identify with. Yet she plays her hand badly, eroding her status in the eyes of her husband and us readers. She was, Aboulela admits, the most difficult character to write. "She's very different from me. It was a tricky balance to keep her getting the reader's sympathy and at the same time, not getting it, because of her prejudice.

"Because the novel was set in this time of Anglo-Egyptian rule, she represented the Egyptian in Sudan, the colonial attitude. Britain and Egypt invaded Sudan alongside each other, with Egypt footing the bill for the expeditions.

"Then with time, it was more Britain ruling and Egypt becoming a lesser partner. In Egypt they had this attitude towards Sudan, that it was the backyard, so she carried this attitude with her and has all these prejudices toward the Sudanese. She saw herself as superior to them. She thought the Sudanese would be completely bowled over by her and would look up to her. She didn't expect to find this entrenched pride and attachment to their own lifestyle and values."

Aboulela's other novels led me to expect a story more blatantly about the Muslim experience, but Lyrics Alley reads like a gripping family saga. The novel's only overtly religious character is the children's tutor, Ustaz Badr, who can quote the Qu'ran from memory. Aboulela is amused by my reaction.

"When you write about a Muslim woman, like I did with my previous novels - Minaret, for example, which is about a woman who starts to wear the hijab - it sets all the alarm bells ringing. When the man is religious it doesn't seem to impact the reader as much. There's a lot about Islam in this novel as well, but because it's from a man's point of view it doesn't have the same impact. But I am glad you brought this up because I think a lot of readers will say that, and it's so interesting. You say you're interested in the issue of women, and it shows how provocative it is for a woman to be religious. Why, I don't know. This was a deliberate choice. I wanted the tutor to be the only one who was religious in the whole novel. I also wanted to be faithful to the characters I was writing about, who I knew. My father's family were not so religious, even though they were pretty traditional and conservative."

Then again, those earlier novels depicted characters wrestling with their faith, whereas here, it's so ingrained as to be invisible to the participants. "It's also the setting," she adds. "The others were set in Britain. If you have this combination of a religious Muslim character in a western setting, you're pressing buttons."

Yet Aboulela has always been sensitive to religious undercurrents in her reading, which encompasses everything from Dostoyevsky to Joanna Trollope. She reminds me that the western canon is deeply infused with the values of Christianity, which I probably don't notice.

"People take for granted when they see Christianity inside novels, but when you come in from a different perspective, as a Muslim, for instance, you can see it's been very much influenced by Christianity. The example I've used before is Jane Eyre: Mr Rochester can't marry Jane because he's already married to Bertha. This is so Christian. In a Muslim situation he can just marry both. Nobody's going to say, 'Oh, this is hitting us on the head with Christianity,' but it's there."

Whatever our religion, or lack thereof, we have our humanity in common. Who hasn't, like her characters, asked that most universal of questions: "Why do bad things happen to good people?"

"This intrigues me," says Aboulela. "Every religion has an answer to this question. If you believe God is good, why does evil exist? In the case of Islam, we believe that God is all powerful. There isn't a fight between good and evil. Everything comes from God, the good and the bad. In Islam there is this emphasis on seeing bad things as tests and trials, or maybe that they're not as bad as we perceive them to be."

For some of us, the litany of life's bad occurrences is a reason for not believing in God. "Yes, and that was one of the reasons I was very enthusiastic to tackle this question. I felt that I could write about it without it being sensational, without it having the sensitivity about it like the hijab." Because it was couched in the context of personal tragedy? "Yes. I could write the Islamic point of view without being as provocative as my other novels, which are read by some people as being assertive of a kind of Muslim identity in the west. So this one is a little bit more philosophical."

• Lyrics Alley is published by Weidenfeld & Nicolson on 16 December, priced 18.99.