Final answer:
Benji Stacy was born with blue skin due to a genetic condition called methemoglobinemia, which disappeared after a few weeks. The condition is related to the descendants of Martin Fugate and reflects how skin color can change over generations.
Step-by-step explanation:
The question pertains to Benji Stacy who was born with blue skin that disappeared after a few weeks. This blue skin color is related to a genetic condition that was prominent in the descendants of Martin Fugate in the hills of Kentucky. The condition, known as methemoglobinemia, is characterized by an elevated level of methemoglobin in the blood, which can give the skin a blue tinge. Over generations, skin color can vary widely among human populations due to evolutionary factors, and it is important to note that this phenotypic expression can eventually change or reverse given different environmental and genetic interactions.