https://www.washingtonpost.com...m_term=.95a8352b5f84

The family that walks on all fours — and why they can’t stand up

In a village of dirt roads and stone dwellings just north of the Turkey-Syria border, a slight rain falls as a hunched man clad in black wobbles down the pavement. At first glance, as seen in a BBC documentary, he appears inebriated. He clings to a stone wall to his left and lurches uneasily. But then he slowly lowers his hands, encased in green slippers, to the muddy ground. Gingerly, he begins to walk away and out of the frame — on all fours.

The man is one of five children in a religious family bedeviled by an unusual condition that has flummoxed and fascinated scientists since the scientific community first discovered them in 2005. The parents are normal. But five of their progeny are quadrupedal. They walk appendages down, bottom in the air.

Here is another article explaining, It’s adaptation to an unforeseen and rare disorder.