To begin with, "Natural" vs "Unnatural" is insanely difficult to define and I don't think it ever has been.

Many people view nature as a perfect sanctuary for human beings and some often advocate the "natural" way to life, but most people don't take into consideration that nature is riddled with life threatening features that are in fact trying to kill you. Neil Tyson Degrasse speaks about this frequently, check out some of his talks on YouTube if you have a chance, he's amazing.

To say that someone has natural aptitude just doesn't make sense to me personally, especially when we have defined "natural" culturally. I am trying to strip away the socialization and focus only on the objective possibilities but I don't even think that is possible, and I don't see a scenario where having natural aptitude for painting or drawing has anything to do with nature at all.