Source: Fatāwā Amunpuri by Shaykh Ghulām Mustafa Zaheer Amunpuri
If a grandmother has breastfed her grandson, is it permissible for him to marry her granddaughter (his cousin)?
No, such a marriage is not permissible.
In this case, the two individuals—the boy breastfed by the grandmother and her granddaughter—are considered raḍāʿī (foster) maternal uncle and niece to one another. This is because the boy becomes the foster son of the grandmother, and thus, the foster brother of her children—including the granddaughter’s mother or father.
Hence, the girl becomes his foster niece, and this is a relationship in which marriage is prohibited.
﴿وَبَنَاتُ الْأُخْتِ﴾
“And the daughters of your sisters (are forbidden to you in marriage).”
Surah al-Nisā’ (4): 23
The word “ukht” (sister) here is general, and includes both biological and foster sisters. Therefore, a foster niece (daughter of a foster sister) is also ḥarām (forbidden) in marriage.
① The boy and girl in question are foster maternal uncle and niece.
② Foster relations carry the same legal prohibitions as blood relations.
③ Marriage between a foster uncle and foster niece is impermissible and invalid.
❖ Question:
If a grandmother has breastfed her grandson, is it permissible for him to marry her granddaughter (his cousin)?
✿ Answer:
No, such a marriage is not permissible.
In this case, the two individuals—the boy breastfed by the grandmother and her granddaughter—are considered raḍāʿī (foster) maternal uncle and niece to one another. This is because the boy becomes the foster son of the grandmother, and thus, the foster brother of her children—including the granddaughter’s mother or father.
Hence, the girl becomes his foster niece, and this is a relationship in which marriage is prohibited.
❀ Allah ﷻ says:
﴿وَبَنَاتُ الْأُخْتِ﴾
“And the daughters of your sisters (are forbidden to you in marriage).”
Surah al-Nisā’ (4): 23The word “ukht” (sister) here is general, and includes both biological and foster sisters. Therefore, a foster niece (daughter of a foster sister) is also ḥarām (forbidden) in marriage.
Conclusion:
① The boy and girl in question are foster maternal uncle and niece.
② Foster relations carry the same legal prohibitions as blood relations.
③ Marriage between a foster uncle and foster niece is impermissible and invalid.
