The Blue Blooded Orphan!
When the Fugate clan was first spotted, they astounded people. In 1822, Martin Fugate, an orphan from France, had just come to the Troublesome Creek area to start a family. Embarrassed by their bluish color, the families retreated further from the community, exacerbating the problem and cutting off contact with the population.
They married cousins, aunts, and other closely related relatives, greatly increasing the chances of inheriting the condition.