She attracted both fans and haters - while also coping with teenage children who weren’t that keen on having a famous mum.
She told Connexion: “I lead the life of an ordinary person, with my ups and downs, just like anybody else. The only difference is I have a lot of imagination.”
There can be no doubt she has put that imagination to good use as a novelist, journalist and screenwriter.
Sarah’s Key was made into a film with Kristin Scott Thomas, and her biography of Daphne du Maurier, Manderley Forever, resulted in all of du Maurier’s books being republished in France.
But she said: “Don’t forget that my first success, Sarah’s Key, was the seventh or eighth book I’d had published. I was already 45, so it was a difficult struggle. I was a mum like anyone else and my job wasn’t very important to my kids. It wasn’t easy, and nor was the huge success of Sarah’s Key. They didn’t like people talking about their mum. They were teenagers at that point and they found it difficult having teachers at school mentioning the book.
“It took some adjustment, and I had to learn to draw the line between my private and my professional life. It’s a bit of the old French saying ‘pour vivre heureux, vivons cachés’ (to live happily, live hidden).”
She said she was amazed at how many people wanted to meet her when her writing career took off. Many want to be writers, and asked her to read manuscripts. Others asked if she can include them in her books.
“I also get people who want to tell me how much they hate me. It’s not frequent, but writers do get haters.”
She is particularly outspoken about gay rights – her latest novel The Rain Watcher is about overcoming homophobia within a family when the lead character is coming out.
“I can’t tell you the amount of hate-mail I got for defending mariage pour tous. I even got handwritten hate letters, and that hit home.
“But regardless of the hate, I think writers should make a stand. I don’t do feel-good books, I’m a feel-sad writer. I tackle dark, deep stuff.”
Daphne du Maurier has always been a major influence, she said. “Book-worming my way through her books as a child was what made me want to write, and the obsession with the personalities of buildings and the dark family secrets within their walls comes directly from her.” Ms de Rosnay, 57, was born in Paris, to a French father and an English mother. She grew up in France, Britain and the US, and thinks of herself as bicultural as well as bilingual. “I consider myself Franco-British, although my official nationality is French.
“My mother believed because she was born in Rome, she could not pass her nationality on to her children. Now, with Brexit, I don’t want to try.”
She described Brexit as depressing. “I didn’t believe for one minute Brexit was going to happen. We were all shocked, just like when Donald Trump was elected. I’m sad to see the mess the Brexit vote has caused.
“Britain seems very divided and I think, increasingly, people are unhappy and want to vote again, but some are convinced Brexit is the answer – which is a disaster. It’s really ruined England’s image for me.
“The killing of Jo Cox shocked me intensely.”
She is even more sad as she loves Britain, she said. “When I was studying at the University of East Anglia in the mid-80s, you could walk around wearing anything and nobody would take any notice.
“It was refreshing, being able to dress how you like, and the music was so fascinating and different.
“Artists like The Cure and Bowie and Depeche Mode were so creative, they had what we call a ‘grain de folie’ (a grain of madness).”
On the other hand, she said she has learned to be proud of being French. “Paris and the rest of France are different things. Paris is a country in itself. I love living here because a whole new generation of creative people are emerging.
“I can see the Eiffel Tower from my window and it’s like my friend. It watches over me.”
The Rain Watcher is set in Paris during a fictitious period of massive flooding.
“When I started writing the book, I didn’t realise how central nature would be to the plot. I was interested in the idea that if the Seine floods, nothing can prevent it. Nobody can prevent a storm, a hurricane, a flood.
“For centuries Parisians have taken for granted they can control the Seine, but as I was writing the book, it flooded badly and just as the book came out, it flooded again. We have to realise that the Seine will flood again, as badly as in 1910 and as in my book, which is sobering, especially as I live near the river. If Paris seriously floods, it will be like the Titanic going down. The city will have to be evacuated, which will be hell.”
The US edition of The Rain Watcher has been published and is available online, while the UK edition comes out in March.
Her coffee table book about artist Tamara de Lempicka (illustrated with photographs by daughter Charlotte Jolly de Rosnay) was published by Éditions Michel Lafon in October.