Much better to leave such procedures until the people concerned have grown up and can decide for themselves, leaving aside the rare cases where there is some genuine abnormality that needs to be corrected.

One thing I hadn't realised until looking something up for this thread is that there is nothing in the Koran requiring circumcision of male Muslims. In a way it's more of a cultural tradition than a formal requirement. There are some Muslims who are opposed to circumcision of children and babies, on religious and ethical grounds. (See here).