Excerpt from Fatāwā Amaanpuri by Shaykh Ghulām Mustafa Zaheer Amaanpuri
If a woman breastfed a child, can that child marry her granddaughter?
Such a marriage is not permissible.
The woman’s granddaughter becomes the foster niece (raḍāʿī bhatījī) of the child, and the child becomes her foster uncle (raḍāʿī chāchā).
Just as marriage between a blood uncle and niece is forbidden, marriage between a foster uncle and niece is also prohibited.
﴿وَبَنَاتُ الْأَخِ﴾
“And (forbidden to you in marriage are) the daughters of your brothers.”
Surah an-Nisā’ (4:23)
This prohibition includes both biological and foster (raḍāʿī) nieces.
Therefore, a child who was breastfed by a woman cannot marry her granddaughter, because the foster relationship established through breastfeeding is treated the same as the relationship by blood.
❖ Question:
If a woman breastfed a child, can that child marry her granddaughter?
❖ Answer:
Such a marriage is not permissible.
The woman’s granddaughter becomes the foster niece (raḍāʿī bhatījī) of the child, and the child becomes her foster uncle (raḍāʿī chāchā).
Just as marriage between a blood uncle and niece is forbidden, marriage between a foster uncle and niece is also prohibited.
✿ Qur’anic Evidence:
﴿وَبَنَاتُ الْأَخِ﴾
“And (forbidden to you in marriage are) the daughters of your brothers.”
This prohibition includes both biological and foster (raḍāʿī) nieces.
Conclusion:
Therefore, a child who was breastfed by a woman cannot marry her granddaughter, because the foster relationship established through breastfeeding is treated the same as the relationship by blood.