A British mother was horrified to learn that the 12-year-old foster child she took in from war-torn Afghanistan turned out to be a 21-year-old terrorist trainee.The gig was up following a visit to the dentist, who estimated that “Jamal” was a decade older that he claimed to beThe mother, identified only as Rosie, became suspicious when she noticed how hairy the “boy” was and how adept he was at firing a rifle.“Adults are playing the system. It’s putting families like mine and society as a whole at risk,” Rosie told The Sun. “I don’t see anything wrong with dental and bone density checks. Some say they are intrusive and degrading. But having a man in your home who’s pretending to be a child is far more intrusive.”After being busted, Jamal threatened to kill Rosie and her three children.