Parental perceptions of sibling differences: towards a theory of sibling differentiation

A hypothesis of 'triadic and tetradic projective identification' is derived from work with nine cases in which family therapy was followed by psychodynamic counselling with the mother. It is suggested, first, that the dimensions of personality in which a parent perceives considerable difference between siblings may be linked to earlier traumatic issues experienced by that parent, especially in the family of origin; and, second, that siblings may identify with their parents' perceptions of difference, leading to differential development.
Case material is used to illustrate the ideas and a small pilot study of six different families is described, which tests a key element of the hypothesis - that personality dimensions in which a parent perceives most difference between siblings will relate more strongly to parental problem areas than dimensions in which a parent perceives least difference between siblings.
Findings give preliminary support to the hypothesis and proposals for further work are presented.