So, to follow your logic of not messing with "Mother Nature", white people and black people, or any other human subspecies, shouldn't breed together either. "Nature" made it so humans of northern Europe didn't need to produce as much melan in their skin because of the lack of UV rays, and needed ligher skin to absorb vitamin D, whereas "nature" made humans of central Africa with a heavy degree of melan to combat the harsh elements of the sun. So, I guess these people shouldn't breed or move to different areas of the world and stick to their "native" land because they only "evolved" there.
I've heard talk like this before... it's in the history books. A certain European leader 60 years ago was also a nature worshiper and thought less of humans as well.