Creative nature v nurture: where are the facts?

Dear Ernie,

Where does creativity come from?

Is it a nature thing? (some sort of idea-secreting gland you need to
exercise, or an on-board pre-existing instinct like my urge to have sex
with weather presenters)

Or is it a nurture thing? (like wearing odd eyewear, talking like it's
South London, or maybe hanging around Ponsonby restaurants with an
angry head full of Pinot)

I hope you can lead the way on this important matter.

Yours sincerely,

Dull from Ditchwater.