Introduction

An invisible relationship

Despite the fact that nearly everyone has a literal sibling, and those without have probably “adopted” a surrogate (Cumming & Schneider, 1961), adult sibling relationships have been one of the more invisible categories of personal relationships in social science research. Even sibling relationships in childhood have received modest attention compared to the parent–child bond (Irish, 1964; Johnson, 1982). This vertico-centric bias was interrupted briefly in the adult literature with the discovery that solidarity with siblings was perceived by older adults (age 50–80) to be “stronger than that which they perceive between themselves and their parents” (Cumming & Schneider, 1961, p. 502). This unexpected finding was credited to the egalitarian character of sibling relationships, a characteristic that is more in tune with the values of American society than the hierarchical structure of parent–child ties. Preference for sibling ties was also credited to the nonobligatory structure of the sibling relationship, which provides a flexibility more suited to the mobility needed by modern nuclear families to follow economic opportunity (Rosenberg & Anspach, 1973).

Subsequent empirical studies, however, did not support these claims. Compared to those of parents and their adult children, geographical availability of siblings, contact frequency (Leigh, 1982), and help exchanges (Scott, 1983; Myers & Dickerson, 1990; Coward, Horn & Dwyer, 1991; Wellman, 1990) were less. Also, the sibling relationship's vitality seemed to depend upon parental kinkeeping (Rosenberg & Anspach, 1973), because, when parents died, sibling interaction was often attenuated (Allan, 1977; Berardo, 1967; Townsend, 1957; Young & Willmott, 1957; Johnson, 1982).