I dunno.
Like the dark tiara primitive, my brains don't work like most other people's brains, too.
It's of course caused by being deaf.
But just because these brains don't work like most other people's brains, doesn't indicate insanity; it merely indicates a different way of looking at things.
My definition of insanity is where an individual purposely and willfully causes damage to himself and to others, in the spiritual, intellectual, and physical senses.
Which pretty much sums up the primitives on Skins's island.