This article examines the strongest position with respect to sex differences in parent-child relationships during childhood and adolescence, namely that both parent sex and child sex contribute so that relationships in the four dyads of mother-son, mother-daughter, father-son, and father-daughter are distinct. The relevant research was divided into three groups: (a) where only a single dyad was studied; (b) where the four dyads were studied, but no tests for differences were conducted; and (c) where the four dyads were studied and tests for differences were carried out. The research was further divided according to the formal aspect of the relationship being investigated (e.g., studies that made mean-level comparisons versus those that examined correlations among relationship variables). The literature that was surveyed contained many claims and assumptions about the distinctness of relationships in the four dyads, but the empirical evidence in support of these claims and assumptions was limited. Only one study with significant difference among all four dyads was found. Often there were findings of interactions between parent sex and child sex, however, but the form of this interaction varied from one study to another, and from one measure to another. Variables associated with findings of interactions between parent sex and child sex were examined. When dyadic distinctness was found it often was for relationship measures of closeness/cohesion and affective reactions. Suggestions are made for future research.