Fostering involves a parent or set of parents looking after someone else’s child, often on a long-term basis, whereas adoption involves in addition the acquisition of a ‘kin’ relationship between such parents and their (adopted) children. Both practices involve the assumption of parental roles by individuals who are not the child’s biological or birthparents, but the addition of *kinship status in adoption makes that concept both more problematic and more interesting. The original ancient Roman notion of adoptio (adoption) was simply one of passing legal authority (potestas) over an individual from one person to another, outside his own †lineage, often for the purpose of making alliances and securing the inheritance of *property.
In Roman times, the ‘adopted’ individual was most often an adult male who continued, even after his adoption, to retain the ties of love and duty toward his own, living parents. With adoptio, the legal authority of the father over his child was broken and a new relationship established with adoptive parents. In contrast, the Roman notion of adrogatio entailed the acquisition of such authority in a case where the adopted person’s own father and father’s father had died, much as modern adoption usually assumes the death or incapacity of the birth-parents. Thus, modern notions of adoption, including anthropologists’ perceptions as to what constitutes the practice cross-culturally, generally combine the legal aspects of the Roman institutions with the nurturing and affective aspects of fostering and ‘true’ parentage. It also has elements in common with ritual kin relationships, such as *compadrazgo, though ironically the very fact of acquiring a legal kinship status arguably makes adoption an aspect of ‘true’ rather than merely figurative kinship. Sometimes adoption is described as a form of fictive kin relation, but the degree of its truth or fiction is a matter of cultural perception (Barnard and Good 1984:150–4). Ethnographically, adoption in this broadly-defined sense is most commonly found in Europe, North America and West Africa.
Both fostering and adoption reveal important cultural assumptions about processes of relatedness and concepts of *personhood. On the island of Langkawi off the coast of Malaysia (Carsten 1991), for example, people are thought to become kin through sharing common food, and thus common substance, and widespread fostering can be related to other ideas about the fluidity and mutability of kinship (a theme more widely encountered in Austronesian societies). Unlike the Malaysians of Langkawi, for many Americans ‘fictive’ kinship, in the etymological sense of kinship that is ‘made’, fits uneasily into EuroAmerican expectations about the givenness of ‘real’ kinship (Modell 1994). In America, then, changing adoption practices (and consequent public debate), work as a kind of mirror image of what is considered to be ‘real’ kinship, and ethnographic research on ‘fictive’ kinship helps clarify unspoken assumptions about what is ‘real’