Detailed description of Billy Black

Billy does not transform in to a Werewolf. His father did and Jacob his son does. I believe that this is because Vampire's did not live in Forks when he was growing up. The werewolves are protectors so when Vampire's are not there, there is no reason for them to be werewolves. The Cullens come back a few years later and the tribe are able to transform into wolves.