[Mr Apple]

"According to Islamic jurisprudence, children of a Muslim father – even an apparently nonpracticing one, such as Obama's father, and irrespective of the mother's faith – are automatically Muslims. Most Muslims around the world agree: A child of a Muslim father is a Muslim. Period."

[RipSawyer]

It could not be otherwise because under Islam a woman is not to be considered to have any bearing on anything, only the man counts.