Marriage of a Hindu male to his wife's mother is:

Under Section 3(g)(ii) of the Hindu Marriage Act, 1955, two persons are within the degrees of prohibited relationship if one was the wife or husband of a lineal ascendant or descendant of the other; accordingly, a Hindu man and his wife's mother (the man being the husband of her lineal descendant) are related by affinity and fall within the degrees of prohibited relationship. Under Section 5(iv) read with Section 11 of the Hindu Marriage Act, 1955, a marriage solemnized between two Hindus who are within the degrees of prohibited relationship is null and void unless the custom or usage governing each of them permits a marriage between the two.