I could see it being natural within the turks since they have less dominate hair color genes (browns and other lighter colors are more common).
Oh and one other thing I forgot to add. It very much has something to do with other hair color as well. The MC1R gene encodes for the melanin in hair and skin and can determine if a persons hair is blonde, black, brown, or red, though it isnt the only gene involved in determining the aesthetics of your hair. But it is very much related and not a separate entity.