What part of "the work is fiction" do they not understand?

"It is of course pleasing to me to know that you like Owls Do Cry. [...] It is unfortunate that the book seems autobiographical, for except for occasional background and the portraits of the parents, the work is fiction. I do have a brother who is an epilectic; he would have to be much modified and sweetened to fit the character of Toby. The opposite process would have to take place in order to render my youngest sister anything like Chicks."

 From a letter Janet Frame wrote to Pat Lawlor of Wellington, dated 17 June 1957, London. (Janet Frame's copy).