America’s most inbred family started with identical twin brothers whose children married each other – causing heartbreaking genetic defects which have left some of them grunting instead of talking.

The quiet Whittaker family grew up in a broken-down property in Odd, West Virginia, and have been known to communicate through grunts and barks.

DailyMail.com can reveal a set of identical twin brothers sparked the family’s history of incest, with the children of Henry and John Whittaker getting married and having their first child in 1937.