The Quileutes have a detailed history of how they came to be shape-shifters and how that aspect of their nature was focused by their first contact with vampires. Essentially, the early Quileutes had the ability to use astral projection, When this ability led to a coup, the rightful chief put his spirit into the body of a wolf. His progeny were able to assume wolf form as well.
The first time a vampire - or "cold one", as the Quileutes called them - entered the Quileutes' land, the tribe discovered that their wolf protectors were able to kill vampires, but it was an almost evenly matched contest. Vampires became the main focus of the Quileute wolves, Over time, the Quileute warriors gained the ability to assume wolf form only if a vampire triggered the reaction.
This history was passed down through oral storytelling. Originally the entire tribe would learn the account; in the last century, however, the sharing became more secretive, passed only from werewolf descendants to the next generation of potential werewolves. All tribe members know the basics, but think of the stories as myths rather than facts.