Yeah u might have to elsewhere to find where talent stems, and as nemo said who knows and can tell whats tallent and whats not.
But missing genes or altered neurological development (or disease like brain-tumor or hemorrhage) could in some cases be a factor, but usually in the most extreme cases, when some of the boundaries in the mind is broken down and the "connection" to creativity get opened up on full throttle! But the difference between genius and insanity a close one