In Mississippi, parental consent is necessary for applicants under the age of 21. In Nebraska, the legal age to marry is 19. Persons younger than 19 must provide parental consent. Family relationship. All US states prohibit marriage between ancestors and descendants, such as grandparents and grandchildren, aunts/uncles and nieces/nephews, or parents and children. 20 states currently allow first cousins to get married. 6 additional states will allow first cousins to marry under certain circumstances (e.g., above a certain age or unable to reproduce). As of 2015, same-sex marriage is legal in all 50 states and the District of Columbia.
