'Realism' is certainly not an outstanding feature of an Agatha Christie novel, but I suppose in her depiction of the people she represents - the privileged upper-middle class - there must be a great element of truth. The mores that dictated the thoughts and actions of the characters she writes about must of necessity be those which governed her own life.
Things have, of course, changed a great deal since Agatha was in her heyday so even this aspect of her writing may no longer be considered 'realistic' but then, we read Agatha for the intricacies of her plots and the ejoyment of a good story well told.
