What do the scholars and experts of shari’ah say regarding my situation? My sisters wants to marry the son of our paternal uncle. That cousin and my brother had the same wet-nurse when they were babies, but we do not know how many times they were nursed. Will it be permissible for my sister to marry this cousin?
There are two possible conclusions based on who the woman was that wet nursed your brother and your cousin. If this was the wife of your uncle or any other woman then it will be permissible for your sister to marry this cousin if she also was not wet nursed by the same woman. As only the original child who was nursed by a woman will have a kinship with other children who were nursed, the original child’s siblings will not.
If the woman who nursed your cousin and your brother was your own mother, then it will not be permissible for your sister to marry that cousin on condition that the cousin was nursed at least five times within the feeding period of a child. As he will now have a milk kinship with your sister.
If it cannot be determined whether he was fed more or less than five times, then according to the Shafi’i and Hanbali jurists, the marriage is permissible as milk kinship is not established unless a child was nursed five times. As there is doubt in whether the child was five times, then this doubt will not overcome certainty in that the nikah is valid. To accommodate for general necessity (‘umum balwa), this is the fatwa that will be acted upon
And Allah ﷻ knows the best
This Fatwa is written by Dr. Hafiz Muhammad Munir Al-Azhari