Famous novelists are asked all the time where they get their ideas. We know this because they complain endlessly about having to answer this question while they are being interviewed by Oprah, or some other luminary about, say, having won the Man-Booker Prize for the ninth time.
No one ever asks me this question, but then I am not a famous novelist, notwithstanding my diligent, yet failed, efforts to break into a world where I get a dust jacket photograph, an advance, and an opportunity to see my work reviewed twice on Amazon by the same reader, a disgruntled shoe salesperson from Alabama. I feel, as some deponents do, like answering that question anyway.
