kinship

n. family relationship, condition of being related by blood or adoption; affinity, natural attraction

Kinship is one of the most basic principles for organizing individuals into social groups, roles, and categories. It was originally thought to reflect biological descent, a view that was challenged by David M. Schneider in his work on symbolic kinship (1984, A Critique of The Study of Kinship). The crux of his argument was that anthropologists had founded the domain of “kinship” on the notions of human reproduction and the biologically defined relatedness of their own Euro-American culture. Human reproduction and notions of biological relatedness cannot be presumed to structure people’s social relationships in other cultural contexts.
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Noun
1. a close connection marked by community of interests or similarity in nature or character; "found a natural affinity with the immigrants"; "felt a deep kinship with the other students"; "anthropology's kinship with the humanities"
(synonym) affinity
(hypernym) relation
(hyponym) rapport, resonance
2. state of relatedness or connection by blood or marriage or adoption
(synonym) family relationship, relationship
(hypernym) relation
(hyponym) affinity, phylogenetic relation

(n.)
Family relationship.
  

Relationship by marriage or, specifically, a blood tie.