Wow, this is an amazing story. If I had cable, I would definetly watch this documentary. In my opinion, it is because of a brain disability that these people walk the way they do, some scientists seem to think otherwise:
LONDON (AFP) - The discovery of a Turkish family that walks on all fours could aid research into the evolution of humans.
Researchers believe the five brothers and sisters, who can walk naturally only on all fours, may provide new information on how humans evolved from four-legged hominids to walk upright.
Nicholas Humphrey, evolutionary psychologist at the London School of Economics, told The Times the discovery opened "an extraordinary window on our past".
"I do not think they were designed to be quadrupeds by their genes, but their unique genetic make-up allowed them to be," he said.
"It has produced an extraordinary window on our past. It is physically possible, which noone would have guessed from the [modern] human skeleton."...
https://news.yahoo.com/s/afp/20060307/sc_af...HBhBHNlYwM5NjQ-
This is both the most interesting and the disturbing. All five of the people are mentally retarded, but mental retardation doesn't cause people to walk on all fours, it would have happened before now. But Its entirely possible that only a couple or even one did it, and the others took it up while watching the parents when they were younger. I plan on watching the documentary on this March 17th on BBC. I want to see what they look like and how they behave. My mother worked at a school for mentally retarded children when I was growing up, for nearly fifteen years. I will be curious to see what kind of "animal" behavior they are actually exhibiting.