No need to adjust the colors on your monitor, or spend time trying to figure out how the image above was altered. It wasn't.

The family pictured above, the Fugates of eastern Kentucky, actually have blue-tinged skin, the result of a condition called methemoglobinemia. It’s caused by a type of hemoglobin that can’t carry oxygen through the blood—and because the blood isn’t oxygenated, it makes skin look blue, lips look purple, and blood look chocolate-colored.

Most people have less than 1 percent of methemoglobin. When that level rises to 10-20 percent, the result is blue-tinged skin. While the genetic condition didn’t seem to have any notable health impact, it did affect the Fugate family psychologically, causing them to retreat from public life.

They also had to deal with the shame associated with inbreeding. Think back to the Punnett squares you had to diagram in 8th-grade science class. The gene that creates methemoglobinemia is recessive, so it likely wouldn’t have been a problem—except that the Fugate family married within itself. This wasn’t uncommon back in the 1800s, when cousins married cousins without a second thought. But as more became known about genetics and the consequences of reproducing with family members, the Fugates’ blue skin became almost like a scarlet letter … or an indigo letter, as it were. And so they withdrew further from society, becoming something of an urban legend in Kentucky.

In the 1960s, Dr. Madison Cawein was able to test two Fugate descendants, Patrick and Rachel Ritchie. “They were bluer’n hell,” Cawein said. “They were really embarrassed about being blue. They wouldn’t come into the waiting room. You could tell how much it bothered them.” After conducting many blood tests, Cawein came to the conclusion that methemoglobinemia was the root of the problem, and determined that he could convert the methemoglobin back by simply injecting a missing enzyme to oxygenate the blood. Strangely, the easiest way to do this was with a chemical called methylene blue. Though the family thought the doctor was completely crazy—after all, how could injecting them with another blue substance make them less blue?—they allowed Cawein to give it a shot.

It worked almost instantaneously. ''Within a few minutes, the blue color was gone from their skin," the doctor said. "For the first time in their lives, they were pink. They were delighted."