Utah Code Title 81. Utah Domestic Relations Code § 81-2-402. Incestuous marriages void

(a) a marriage between a parent and a child;

(b) a marriage between an ancestor and a descendant of any degree;

(c) a marriage between siblings of the half or whole blood;

(d) a marriage between an uncle and a niece or nephew;

(e) a marriage between an aunt and a niece or nephew;

(f) except as provided in Subsection (2), a marriage between first cousins; or

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

(a) both parties are 65 years old or older; or

(b) if both parties are 55 years old 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.