Short answer
Yes. A woman who nurses a baby within its first two years becomes its milk mother, her husband its milk father and her children its milk siblings, and marriage between them is forbidden for life. In the Hanafi school even one feed counts; the Shafi'i and Hanbali schools require five separate feeds.
Any amount of milk that reaches the baby's stomach within the first two years creates milk kinship, whether by suckling or from a cup or bottle. The milk relatives become mahram as blood relatives do, but they do not inherit from each other or owe maintenance.
Other madhhabs
- Shafi'i
- Only five separate feeds within two years create milk kinship.
- Hanbali
- Five separate feeds, in the relied-upon view.
Explanation
The Quran lists "your milk mothers who nursed you and your sisters through nursing" among those you may never marry, and the Prophet ﷺ said that nursing makes unlawful what blood kinship makes unlawful. The Hanafi and Maliki schools take the ayah at its general wording, so any feed counts. The Shafi'i and Hanbali schools rely on reports that one or two sucks do not count and set the number at five.
Who becomes related:
- The nursing woman: milk mother. Her husband, whose child produced the milk: milk father.
- Their children, before or after: milk brothers and sisters of the baby.
- Their parents and siblings: milk grandparents, aunts and uncles.
- Only the nursed baby is related. The baby's own brothers and sisters are not related to the nursing family, and may marry into it.
What changes: milk relatives can see each other as mahram do and can travel together, and marriage is forbidden. They do not inherit from each other, and there is no duty of maintenance.
Doubts: if you are unsure whether a feed happened, or how many, ask a mufti before any marriage between the families. Pooled donor milk from unknown women raises the same problem, which is why many Hanafi scholars advise against milk banks that do not record donors. The nursing period itself is explained in how long to breastfeed, and its use in adoption in adoption and mahram.
Ask a mufti about your own case. This answer explains the general ruling. When the details of your situation matter, as they do here, ask a qualified mufti and give them the full facts. Where to ask a scholar.
The evidence
Quran, Surah An-Nisaa 4:23
حُرِّمَتْ عَلَيْكُمْ أُمَّهَٰتُكُمْ وَبَنَاتُكُمْ وَأَخَوَٰتُكُمْ وَعَمَّٰتُكُمْ وَخَٰلَٰتُكُمْ وَبَنَاتُ ٱلْأَخِ وَبَنَاتُ ٱلْأُخْتِ وَأُمَّهَٰتُكُمُ ٱلَّٰتِىٓ أَرْضَعْنَكُمْ وَأَخَوَٰتُكُم مِّنَ ٱلرَّضَٰعَةِ وَأُمَّهَٰتُ نِسَآئِكُمْ وَرَبَٰٓئِبُكُمُ ٱلَّٰتِى فِى حُجُورِكُم مِّن نِّسَآئِكُمُ ٱلَّٰتِى دَخَلْتُم بِهِنَّ فَإِن لَّمْ تَكُونُوا۟ دَخَلْتُم بِهِنَّ فَلَا جُنَاحَ عَلَيْكُمْ وَحَلَٰٓئِلُ أَبْنَآئِكُمُ ٱلَّذِينَ مِنْ أَصْلَٰبِكُمْ وَأَن تَجْمَعُوا۟ بَيْنَ ٱلْأُخْتَيْنِ إِلَّا مَا قَدْ سَلَفَ ۗ إِنَّ ٱللَّهَ كَانَ غَفُورًۭا رَّحِيمًۭا ﴿٢٣﴾
Prohibited to you [for marriage] are your mothers, your daughters, your sisters, your father's sisters, your mother's sisters, your brother's daughters, your sister's daughters, your [milk] mothers who nursed you, your sisters through nursing, your wives' mothers, and your step-daughters under your guardianship [born] of your wives unto whom you have gone in. But if you have not gone in unto them, there is no sin upon you. And [also prohibited are] the wives of your sons who are from your [own] loins, and that you take [in marriage] two sisters simultaneously, except for what has already occurred. Indeed, Allah is ever Forgiving and Merciful.
Nursing creates a lasting bar to marriage.
Sahih al-Bukhari 2645
Sahih... يحرم من الرضاع ما يحرم من النسب ...
"What is made unlawful by blood kinship is made unlawful by nursing."
Milk relatives take the marriage rules of blood relatives.
Sahih Muslim 1450
Sahih... لا تحرم المصة والمصتان ...
"One or two sucks do not make marriage unlawful."
The basis of the Shafi'i and Hanbali requirement of more than a little.
Where the ruling is recorded
- al-Hidaya, Kitab al-Rada'. Any amount within the period creates kinship in the Hanafi school.
- Minhaj al-Talibin, Kitab al-Rada'. The Shafi'i condition of five feeds.
- al-Mughni (Ibn Qudama), Kitab al-Rada'. The Hanbali view and the reports behind it.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.