It gives nothing away to reveal that a man dies in the opening pages of Ghana Must Go , Taiye Selasi's debut novel. The man, Kweku, the patriarch of a troubled African family, dies several more times in the book, with increasing detail as the effect of his death on his children is examined. "The story and these six characters came to me as a whole," she says, "and this book was much something I received rather than something I decided."

Selasi, who has just been included in Granta 's Best of Young British Novelists, is in the middle of a publicity whirl. When we speak she is on a crowded train en route to another event. She was picked for the prestigious list even before her novel was even published, but the magazine published a short story of hers in its F Word issue on feminism, in 2011.

Publication came relatively late for Selasi. After studying and a job in corporate life, her 30th birthday proved to be the falling axe. “I gave up my job to write, but after a few months nothing was happening. A friend invited me to go on a yoga retreat in Sweden. One day I emerged from the shower and told her I had found my first novel – in the bathroom,” she says with a laugh.

Selasi immediately began work on the story of an African family, the Sais. Set over several decades, Ghana Must Go is as broad in its geography – Ghana, Nigeria, the US – as it is in its thematic scope, but character is its core. Kweku has previously abandoned his wife, Fola, and their children Olu, twins Kehinde and Taiwo, and Sadie. Early in the novel two of the siblings talk across the dark of their bedroom, trying to make themselves happier with different versions of their lives.

“I’m telling my family story a lot these days, and it occurs to me that I’m also creating it. My sister lives in the US, my mother in London, my father in Saudi Arabia. I create this idea of my family, which is spread across the globe, so I create this idea of us as ‘whole’ in telling our story. In the story, we create units and connectedness, and in telling stories we sustain a sense of belonging.”

Selasi’s mother is Nigerian, her father is Ghanian and she herself was born in London, studied in the US and now lives in Rome.

Her connection to her father is central to her sense of identity, as she discovered some years ago at a wedding. A man at the same table assumed her father had several wives. “I was ashamed in that moment, because he had assumed something about my family” – that her father was polygamous, because they were African. “I was angered by that assumption, because it seemed to arise out of that monochromatic view of Africa which I encounter so often. I was ashamed that anyone in my family perpetuated any of the stereotypes that I find so personally offensive.”

For Selasi, the casualness of this racism was more disturbing. In the novel, one character observes “the kind of poverty he had only seen in children living near the equator”, and Selasi was wary of being polemical about African’s socioeconomic identity.

“What’s heartbreaking about racism is the assumption that something happens because someone is black, or African. People have very myopic expectations of narratives concerning African people. For me, it’s about the humanity of the characters, and the images that I see – that all of us see – don’t represent the Africa that I know.”

A few years ago she published an essay examining her own identity, which included the phrase "Afropolitan", referring to second-generation African children. Her sense of her Africanness is strong, but she regards it as is problematic to group writers based on place or geography. Selasi read Chinua Achebe's 1975 essay An Image of Africa , and it had a profound affect on her views of literature.

"He talks about the problems with Joseph Conrad's Heart of Darkness but, more broadly, about the way Africa and African people are represented in western literature. That for me changed everything. It let me know that there was something wrong with the place that people who look like me and have names like me occupy in the literature that I love."

More recently Selasi has struck up a friendship with Toni Morrison. The two met while Selasi was studying at Oxford, and Morrison gave her a creative deadline, which resulted in The Sex Lives of African Girls for Granta 's feminism issue.

“To me there’s no single state of feminism right now, because there is no single state of women. In order to engage with the notion of feminism one has to locate oneself in a particular place and class and go from there. My own version of it is important. It’s something I inherited from my mother, which is the strong sense that a woman should be able to express herself in the world exactly as she wishes, without being undermined just because she is female.”

Perhaps Selasi’s most surprising confidant is the former Labour Party leader Dick Spring – she has a master’s in international relations, and the two met at a conference. The pair often catch up on her annual visit to Ireland. This year she may return, between working on a screenplay and beginning her second novel. “One time my mother, sister and I caught a boat to Skellig Michael,” she says. “I might catch up with Dick next time – he’s a good friend.”

Ghana Must Go is published by Viking