• A person is a relative by affinity (1) to any blood or adopted relative of his or her spouse, and (2) to any spouse of his or her blood and adopted relatives. Based on the theory that marriage makes two people one, the relatives of each spouse become the other spouse’s relatives by affinity. See AFFINITY.
relative by affinity
A person who is related not by marriage or by blood or by adoption, but solely as the result of a marriage.