from wikipedia:
Hypertrichosis,
congenital generalized Hypertrichosis or
werewolf syndrome is a medical term referring to a condition of excessive body
hair.
Werewolf syndrome comes from the characteristics of a mythological werewolf of which the person is completely covered in
hair or
fur. It can be generalized, symmetrically affecting most of the torso and limbs, or localized, affecting an area of skin. It may be mild or severe. In most cases, the term is used to refer to an above-average amount of normal body hair that is unwanted and is an aspect of
human variability.
In medical practice, once generalized hypertrichosis has been distinguished from
hirsutism, it is most often considered a
variation of normal, primarily resulting from
genetic factors.
Most of the people recently featured in the media with hypertrichosis are from the Aceves clan of Loreto, Zacatecas, Mexico, some of whom have emigrated to the United States. Many of them have worked for circuses. The brothers Victor Ramon "Danny" Ramos and Gabriel "Larry" Ramos have worked as acrobats. Their cousins, Jesus "Chuy" Aceves, and his sister, Lili, have worked in sideshows.
Although the statistic has been cited that this only occurs for 1 out of 10 billion people,19 people alive today have hypertrichosis out of ~6.5 billion people in the world, makes for an average of 1 in 340 million.