Incest between brothers and sisters is rooted in a failing of the parental functions; a failing that has to do both with the fragility of the prohibition on incest and the maternal protective function. Violence then becomes the dominant and defining link in the family structure. A confusion in the positions of individuals is then put in place, as well as a repetition of violence in the subsequent generation. In this article we discuss this configuration that is specific to some incidents of incest between brothers and sisters.
Incest within the sibship cannot be summarized as an identification with the aggressor (with the primal father) since the sexual element is to be included in the act of violence. As this is the case, we put forward a hypothesis that the aggressor-son’s incestuous act is an echo of the incestuous fantasy/non-fantasy present in the father. The incestual of the father is expressed through the bequeathing of a position of privilege to one of the children. This position is then the point of expression of the incestuous violence. The child who exists on the side of the father’s failing imaginary would be the brother to destroy. The incestuous act would be the attempt to form a symbolic link with the father by killing the brother who occupies that place, an attempt that is at the same time inscribed in the impossibility of confronting a father who resembles the father of the primal horde.