I am going to cut & paste whole a comment from Jemima Harrison of Passionate Productions, who is behind the upcoming documentary about the family who exhibits quadruped locomotion:
The mutation on 17p has been identified by a Turkish/German team in Berlin headed by Professor Stefan Mundlos. They suggest, some would say controversially, that this mutation could have knocked out a gene that plays a role in bipedal walking, atavastically exposing an earlier form of walking. Professor Humphrey believes, however, that this mutation has merely caused the cerebellar hypoplasia confirmed by MRI scans, and which makes it so difficult for them to balance upright. He argues that it's likely to be a conjunction of other factors that has kept the siblings on all fours. These include what seems to be a familial predisposition to bear-crawling as children (all 19 children, including all the healthy ones, did it), and a mix ...
