OK, Sistani on breastfeeding: "2497. It is recommended that the wet-nurse, whose services are obtained for a child, should be Shia Ithna-Asheri, sane, chaste, and good looking; and it is Makrooh [undesired] for a wet-nurse to be a non-Shia Ithna-Asheri or ugly, ill-humoured or illegitimate. It is also Makrooh to entrust the child to a wet-nurse who has given birth to an illegitimate child."