We have taken an orphan into our home. For three months, my wife fed him on her own expressed breastmilk by using a breast pump. Does this method of nursing establish a non-marriageable kinship between him and my wife and children?

 

The Prophet (peace and blessings be upon him) said: "Suckling establishes prohibition in marriage in the same way as blood ties" (Bukhari and Muslim).

Elements of prohibited suckling

The nursing woman must be:

- Alive at the time the milk is extracted from her.
- Potentially able to give birth, whether she is a virgin, married, a divorcee, or a widow.

States of breastmilk that establish milk kinship:

Breastmilk may not necessarily remain in its (natural) state at the time it is expressed. Imam al-Nawawi, the Shafi'i scholar, stated in Rawdat al-Talibeen:
"If the state (of breastmilk) changes i.e. it goes sour, curdles, ferments, turns into cheese, butter, buttermilk or mixed with bread, all of the above create an impediment to marriage because the milk reaches the stomach of the nursling and it is nourished on it. Mixing the milk with any other foodstuff similarly creates an impediment to marriage."
To establish prohibition, the milk must reach the stomach of a live infant whether through the act of suckling or pouring the expressed milk into its mouth until it reaches the stomach. It is not a condition that the milk reaches the infant's stomach in any one single manner; the feedings may include suckling the infant, pouring the milk into his mouth (with no act of sucking), etc. The important thing is the number of feedings that establish milk kinship.

Age:

The age of the infant must not exceed two lunar years. They are calculated starting from the day the child was born.

The Ruling

If the infant mentioned in the question has consumed your wife's breastmilk five times or more during the first two years of its life, then the child is your son through nursing, and a brother through nursing to your daughters. He cannot marry any of your daughters, because the milk establishes kinship, which is a prohibition to marriage. It is permissible for him to mix (freely) with them as a full brother.

God Almighty knows best.