Prohibited Marriages: There is a distinction between prohibited marriages that will not be recognized by the state regardless of the capacity of the parties (and are, therefore, invalid or void), and those that could be valid but are voidable due to some incapacity of the parties.
Two mirror-image statutes provide:
"No man shall marry his mother, grandmother, daughter, granddaughter, stepmother, grandfather's wife, son's wife, grandson's wife, wife's mother, wife's grandmother, wife's daughter, wife's grand-daughter, nor his sister, brother's daughter, sister's daughter, father's sister, or mother's sister, or cousin of the first degree. " MCL 551.3; MSA 25.3.
"No woman shall marry her father, grandfather, son, grandson, stepfather, grandmother's husband, daughter's husband, granddaughter's husband, husband 's father, husband 's grandfather, husband's son, husband's grandson, nor her brother, brother's son, sister's son, father's brother, mother's brother, or cousin of the first degree. " MCL 551.4; MSA 25.4.
"No marriage shall be contracted whilst either of the parties has a former wife or husband living, unless the marriage with such former wife or husband, shall have been dissolved." MCL 551.5; MSA 25.5.
Thus, the law prohibits marriages up to 2 generations apart (up to grandparents; down to grand-children), and also prohibits many but not all "in-law" (e.g., son's wife and wife's mother, but not brother's wife or wife's sister) and "step" unions (e.g., stepmother). A decreasing number of states prohibit marriages based upon affinity. Michigan's Criminal Sexual Conduct statutes, it might be noted, use the very broad phrase "the actor is related to the victim by blood or affinity to the fourth degree. "