A two headed baby os of a natural origin, so how can it be unnatural?

Now, a two headed baby is not normal, but normal and natural are two different things.

Before doctors chose to perform operations, they generally make sure that the two headed baby or person will likely survive the operation. If the doctors think that the operation will definitely kill them, and that they can live with two heads, they allow them to have two heads.

Interesting fact, a couple of Siamese twins were married, and each twin had a wife! Must have made for some interesting times!