I'm always asked if my background influenced my writing. I doubt I'd be writing about the complexity of family life without having been forced to confront my past. However, it's a tiny part of the challenge of writing a full length novel, after all I've not had dementia (yet!), and can't remember being five...
Writing believable characters, is everything. Would they really think, do, say that, is the question I ask after every line. Did you find the characters in Call Billy or Short Cuts believable?