Would I need to breastfeed a baby boy or girl to adopt an orphan.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If what is meant by adoption is that the breastfed child becomes a prospective Mahram (a non-marriageable relative) for the breast feeder woman and her daughters, for example, then yes, for he would not be considered Mahram unless by one of the three conditions of prohibition, namely: blood relation, breastfeeding, and relationship by marriage. If the household would like the child to be Mahram for them, they have to breastfeed him in a sufficient way that makes him a Mahram; i.e., five full and sufficient breast-feeds before the child completes two years of age. But if what is meant by adoption is joining the child to the family in terms of affiliation, that is, to be related to someone other than his father, then this is prohibited. This is based on the Prophet's saying: “Whoever claims affiliation (in terms of lineage) to anyone other than his father, then he is a disbeliever.” [Al-Bukhari, Muslim, and others]

This unlawful act (adoption) cannot be made lawful by means of breastfeeding. Furthermore, if what the questioner means is getting reward by caring for an orphan, then this does not necessitate breastfeeding him.

For more benefit on the ruling of adoption, please refer to Fatawa 119119, 84422, and 82371.

Allah knows best.