Generally speaking, psychoanalysis has focused far less on sibling rivalry than on its Oedipal counterpart. The author explores the reasons for this discrepancy from what is known of Freud's personal background as reported, inter alia, in his self-analysis. He reviews the theories that Jacques Lacan and Melanie Klein put forward as regards fantasies about sibling rivalry. Lacan's referential framework was mainly Gestalttheorie with its implications for the advent of what he called the Identity of the Subject, whereas Klein was more concerned with the theory of object relations and the early stages of the Oedipus complex. The author then goes on to examine Tustin's work with autistic children and her description of the ‘nest of babies’ fantasy, which is seen as linked to the child's emerging sense of otherness.