Author Mark Haddon has said that he is “puzzled and fascinated by the way in which some readers remain untroubled by the content of a novel but deeply offended by the language in which it is described”, after his award-winning book The Curious Incident of the Dog in the Night-Time was pulled from a summer reading list at a Florida school over parental concerns about swearing.

Winner of the Whitbread Book of the Year which is now also a prize-winning play, The Curious Incident is narrated by a 15-year-old with Asperger’s Syndrome, as he embarks on an investigation into the death of his neighbour’s dog. It had been given as a summer reading assignment to students at Lincoln High School in Tallahassee, Florida. But according to local paper the Tallahassee Democrat, after the school’s head received “concerns over the delivery of the text” in emails and telephone calls from parents, the assignment was cancelled in order to, in the head’s words, “give the opportunity for the parents to parent”.

One parent told the paper: “I am not interested in having books banned. But to have that language and to take the name of Christ in vain – I don’t go for that. As a Christian, and as a female, I was offended. Kids don’t have to be reading that type of thing and that’s why I was asking for an alternative assignment … I know it’s not realistic to pretend bad words don’t exist, but it is my responsibility as a parent to make sure that my daughter knows what is right or wrong.”

The Tallahassee Democrat tallied up the appearances of swear words in the novel: “the f-word is written 28 times, the s-word 18 times, and the c-word makes one appearance – in Britain that word is less charged than it is in the US,” reported the paper. “A few characters also express atheistic beliefs, taking God’s name in vain on nine occasions.”

Facebook Twitter Pinterest Seeing ****s … Luke Treadaway as Christopher in the National Theatre production of The Curious Incident Of The Dog In The Night-Time Photograph: Tristram Kenton

Haddon told the Guardian by email that “one irony” about the situation was that Curious Incident is “not just a novel that contains swearing but a novel about swearing”.

“Christopher is completely unaware of the offence that swearing is intended to cause and therefore it simply washes over him,” said the novelist, adding that while he has received complaints in the past about the novel’s language, “no-one has ever complained that the book is about a mother abandoning her son or that it contains a scene in which a father hits his son”.

“But many people have complained that it contains the word ‘cunt’,” said Haddon. The word appears when Christopher is on a train to London, and is noticed by two men. “Come on, shift it, you daft cunt. I need more beers before I sober up,” one of them says to the other.

The Curious Incident has been the subject of controversy in the past. According to the American Library Association, it was removed from the Lake Fenton, Michigan summer reading programme in 2010 after parental complaints about “foul language”.

“The assumption is that I should be morally affronted when this happens – and it has happened surprisingly often – but the truth is that it always generates a really interesting debate among school kids and librarians and parents, not just about Curious, but about literature and freedom and language, and this is an undeniably good thing,” said Haddon. “I have no way of proving it, but my suspicion is that more people read the book as a result and read it with more attention and interest than they might have done.”

With other parents criticising Lincoln High for participating “in an act of censorship”, the Florida school’s assistant superintendent Scotty Crowe told the Tallahassee Democrat that “we take censorship very seriously”, but that Curious Incident “wasn’t a part of the true curriculum”.

“We use summer reading as a way to keep kids engaged over the summer. The book will remain on the media centre shelves and is not being banned,” Crowe added.