It really happened: Six generations of inbreeding spanning the years 1800 to 1960 caused an isolated population of humans living in the hills of Kentucky to become blue-skinned.
The startlingly blue people, all descendants of a French immigrant named Martin Fugate and still living near his original settlement on the banks of Troublesome Creek when hematologists studied them in the 1960s, turned out to have a rare blood condition called methemoglobinemia. A recessive gene was pairing with itself to change the molecular composition of their blood, making it brown as opposed to red, which tinted their skin blue.
more
Will Humans Eventually All Look Like Brazilians? - Yahoo! News
related
http://www.indiana.edu/~oso/lessons/Blues/TheBlues.htm
The startlingly blue people, all descendants of a French immigrant named Martin Fugate and still living near his original settlement on the banks of Troublesome Creek when hematologists studied them in the 1960s, turned out to have a rare blood condition called methemoglobinemia. A recessive gene was pairing with itself to change the molecular composition of their blood, making it brown as opposed to red, which tinted their skin blue.
more
Will Humans Eventually All Look Like Brazilians? - Yahoo! News
related
http://www.indiana.edu/~oso/lessons/Blues/TheBlues.htm