The goal of this paper is to relate formal analysis of kinship terminologies to a better understanding of who, culturally, are defined as our kin. Part I of the paper begins with a brief discussion as to why neither of the two claims: (1) kinship terminologies primarily have to do with social categories and (2) kinship terminologies are based on classification of genealogically specified relationships traced through genitor and genetrix, is adequate as a basis for a formal analysis of a kinship terminology.The social category argument is insufficient as it does not account for the logic uncovered through the formalism of rewrite rule analysis regarding the distribution of kin types over kin terms when kin terms are mapped onto a genealogica...