American author Marisa de los Santos writes novels about unconventional families and their secrets.

In her best-selling debut novel Love Walked In (2005), a single woman named Cornelia suddenly finds herself playing surrogate mother to the hitherto-unknown 11-year-old daughter of her feckless boyfriend.

Her follow-up novel, Belong To Me, which debuted at No. 5 on The New York Times bestseller's list in April, is a sequel of sorts. Cornelia, now happily married to a childhood friend, moves from the city to a suburb outside Philadelphia, where she forges new friendships and uncovers an unexpected secret.

Over the phone from Wilmington, Delaware, the writer, 41, reveals to LifeStyle that her own family has its share of skeletons in the closet.

The former University of Delaware assistant professor of English said that her Filipino father, a general surgeon born in Cebu City, moved to the United States as a young man. There, he met and married her mother, a nurse who is white.

The writer and her younger sister were born in Baltimore, Maryland, and raised in northern Virginia, where they led a 'conventional' life. Then one day, when she was 14, her father told them that he had been married once before and had two sons back in the Philippines.

'That might be why we never visited the Philippines,' says the author with a laugh. She first visited the country in her early 20s, and has since visited more than five times.

Furthermore, her father's ex-wife and sons were still very much a part of his family, even living with his parents and an unmarried sister: 'The way the Philippines is, the extended family is much more a part of everyday life than it is here. So even after my father left, these two boys and my dad's ex-wife continued to be an integral part of that family.'

But the most shocking news for the then teenager was yet to come. 'The reason he finally told us was that the older of his two sons, who was in his 20s, was going to come and live with us,' she says.

That experience was, in the author's own words, 'a disaster'.

'My sister and I were goody-two-shoes, always getting straight As, but he was a different kind of person. He was angry that his parents were not together, and he was just so much wilder then my sister and I,' says the writer, who holds a PhD in English and creative writing from the University of Houston and who published a collection of poetry, From The Bones Out, in 2000.

Her half-brother left her family after a year to live with some of his mother's relatives in California. But there is a happy ending. Now that they are all adults, she and her sister are on good terms with their half-brothers, both of whom now live in the United States. The older brother joined the navy while the younger is a respiratory therapist.

'We don't talk that much, but we send Christmas cards and letters,' she says.

'There is a lot of goodwill. We care about each other and keep up with news on each other's kids. We have figured out a way to be a part of each other's lives.'

And in a final twist, it is her parents, both retired, who now live in Cebu City, near her father's family. They emigrated four years ago.

'My mother has multiple sclerosis and is wheelchair-bound, and they decided to move to the Philippines as, being middle- class, you can easily have several live-in helpers there,' she says.

The writer and her husband David, an associate professor of American literature at the University of Delaware, have since visited her parents twice, along with their two children, Charles, eight, and Annabel, six.

'We spend a huge amount of time with family, and when I am there I don't feel like a tourist. It is mostly about having lots of kids running around and lots of really good food,' she says.

She even plans to set part of her next book - which is unrelated to the first two - in the Philippines. It is about three once-close college friends who have lost touch with one another, until one of them suddenly disappears, and the others are approached by the missing woman's sister for help.

'It is not so much a mystery as it is a story of these relationships - how they became friends, why they stopped being friends and what it is like being in each other's lives again,' she says.

'All my books have a plot - I believe in plot - but I feel like it is really inner journeys which are most interesting to me.'

Love Walked In ($17.33) and Belong To Me ($35.31) are available from Books Kinokuniya. Prices include GST.