1. Affinity- 1.a close agreement; 2.the relation that one spouse has to the blood relatives of the other spouse; relationship by marriage;3. any familial relation resulting from a marriage.
2. Consanguinity- the relationship of persons of the same blood or origin.
3. Adoption- the creation by judical order of a parent-child relationship between two parties who usually are unrelated; the relation of parent and child created by law between persons who are not in fact parent and child.
Source: Bryan A. Garner, "Black's law dictionary"