It is illegal for first cousins to marry in South Dakota. The state’s law prohibits marriages between first cousins as well as half-first cousins, regardless of whether the relationship is by blood or through adoption. This ban has been in place since the 1860s and remains strict, with no exceptions for age, fertility, or other conditions.
South Dakota law explicitly includes both “whole blood” (children of full siblings) and “half blood” (children of half-siblings) cousins in this prohibition. Marriages between first cousins once removed or more distant relatives, such as second cousins, are allowed.
To summarize:
- First cousins and half-first cousins: Marriage is prohibited, with no exceptions.
- First cousins once removed and more distant relatives: Marriage is allowed.
- Legal context: The prohibition applies to both blood and adopted relationships, and the law has remained unchanged for over 150 years.
Marriage applications in South Dakota may not specifically ask about blood relations, but couples are legally required to confirm there are no barriers to their marriage, which includes not being first or half-first cousins.
Sources:
- https://en.wikipedia.org/wiki/Cousin_marriage_law_in_the_United_States
- https://findalawyerinsd.com/pages/areas-marriage
- https://dataminingdna.com/can-first-cousins-marry-in-south-dakota/
- https://sdlegislature.gov/Statutes/25-1-6