The Prophet Muhammad (peace be upon him) once said that a person who cares for an orphaned child will be in Paradise with him, and motioned to show that they would be as close as two fingers of a single hand.  An orphan himself, Muhammad paid special attention to the care of children.  He himself adopted a former slave and raised him with the same care as if he were his own son.

However, the Qur’an gives specific rules about the legal relationship between a child and his/her adoptive family.  The child’s biological family is never hidden; their ties to the child are never severed.  The Qur’an specifically reminds adoptive parents that they are not the child’s biological parents:

 …Nor has He made your adopted sons your (biological) sons.  Such is (only) your (manner of) speech by your mouths.  But Allah tells (you) the Truth, and He shows the (right) Way.  Call them by (the names of) their fathers; that is juster in the sight of Allah.  But if you know not their father’s (names, call them) your brothers in faith, or your trustees.  But there is no blame on you if you make a mistake therein.  (What counts is) the intention of your hearts.  And Allah is Oft-Returning, Most Merciful.

(Qur’an 33:4-5)