(a) A husband and wife are related to each other in the first degree by affinity. For other relationships by affinity, the degree of relationship is the same as the degree of the underlying relationship by consanguinity. For example: if two individuals are related to each other in the second degree by consanguinity, the spouse of one of the individuals is related to the other individual in the second degree by affinity.
(b) An individual’s relatives within the third degree by affinity are:
(1) anyone related by consanguinity to the individual’s spouse in one of the ways named in § 573.023(c); and
(2) the spouse of anyone related to the individual by consanguinity in one of the ways named in § 573.023(c).