Sororate marriage refers to marriage between a husband and his wife's sister. This usually happens when the husband is widowed; and there is still a need to strengthen the bond between the two clans (the husband's and the wife's). This is an ancient practice seen in Chinese, Inuit, Sioux, and Swazi people, among others. The wife's infertility is also reason for sororate marriage.
More About Sororate Marriage
There are some evidences that sororate marriage was practiced by Anglo-Saxon peoples. There is the Deceased Wife's Sister's Marriage Act of 1907, where the United Kingdom's parliament legalized the marriage of a man to his dead wife's sister. Regardless, the practice of sororate marriage is still uncommon, given the social disapproval that comes with it.
