How do bones become double jointed?

Question: How do bones become double jointed?
- Keywords:
  body,
  bone,
  double,
  jointed
Asked by to Edward, Ian, Mathew, Naomi on 25 Jun 2014. This question was also asked by .
- Naomi Osborne answered on 25 Jun 2014:
  
  Many people who are double jointed are born with the ability to stretch their joints further than most people because they have shallow joint sockets (they don’t actually have two joints – this is an incorrect term used and it’s actually called hypermobility!)
  
  Otherwise it can be causes by injuries and illnesses that affect the joints – such as having weak ligaments.
  
  You can also train yourself to become hypermobile by stretching your muscles during exercise, such as Yoga.
  
  Are you “double jointed”?

Question: How do bones become double jointed?