The hair is caused by a one-in-abillion genetic condition known as hypertrichosis universalis
The essay focuses on two 'hairy girls', the Gonzales sisters, who had a condition called hypertrichosis universalis
that caused most of their bodies to be covered in hair.
Ferdinand's castle, Ambras, has since given the name to Gonsalus's condition: hypertrichosis universalis
congenita, Ambras type (McCusick, 2004).