Utah Code Title 30. Husband and Wife § 30-1-1. Incestuous marriages void

(a) marriages between parents and children;

(b) marriages between ancestors and descendants of every degree;

(c) marriages between siblings of the half as well as the whole blood;

(d) marriages between:

(e) marriages between first cousins, except as provided in Subsection (2);  or

(f) marriages between any individuals related to each other within and not including the fifth degree of consanguinity computed according to the rules of the civil law, except as provided in Subsection (2).

(a) both parties are 65 years of age or older;  or

(b) if both parties are 55 years of age or older, upon a finding by the district court, located in the district in which either party resides, that either party is unable to reproduce.