It's a question that Guardian reviewer Lee Robson takes David Lodge to task for not asking in Lodge's newly published collection of essays Lives in Writing. Robson answers it himself with reference to the critic Frank Kermode's discussion (in his memoir) of 'what kind of person makes a good novelist'. Kermode himself, a 'champion defeatist', was discouraged from trying to be a novelist by the suggestion that he hadn't had enough real-life experience. He came to the conclusion that people who made good novelists, such as William Golding and Iris Murdoch, were 'people very unlike him'. They had a 'capacity' that he lacked, to write convincingly about things they hadn't actually experienced.
Robson however points out that both Golding and Murdoch, whose early novels were rejected, had to develop that ability (that they too at one point lacked it), and comes to the conclusion that the novelist is rather
'...not someone who can [just] mix autobiography and invention, as Lodge ... suggests, but someone whose sensibility contains a balance of the intuitive and the pragmatic, the introvert and the extrovert, the better to create fiction that is neither too personal nor too [mired in technical facts].'Which seems about right, if you add in the need for determination and maybe obsession - and perhaps especially in the current commercial literary climate.
Lodge, it seems, is complaining about the kind of reductive biographical readings of fiction about which I've frequently complained here, those that reduce fiction to mere biography or indeed 'disregard' or devalue it if it doesn't fit known biographical facts about the author. However, Robson in turn complains that this 'blinds him to more desirable forms of biographical insight into the writing - and non-writing - of novels', and points to the life experiences that do indeed make people novelists or non-writers, such as Frank Kermode's unhappy childhood that left him with 'a lifelong sense of himself as a failure', the childhood nurturing that, conversely, gave Philip Roth his supreme literary confidence, and the family habits that fed Muriel Spark's subversive wit.
I haven't read Lodge's book, but it seems to me harsh to chastise him for not taking on a different project from the one in which he is engaged - Lodge is apparently concerned with our reading of texts, whereas Robson's interest here is essentially biographical and sociological - but I find Robson's point interesting and astute, nevertheless.