Someone with DID acts like Sybil
Media representations of dissociative identity disorder evoke images of severe disturbance: alter Eve Black trying to kill primary Eve White's daughter, or Sybil walking away from her students and into a river, fully dressed. The 1953 movie "The Three Faces of Eve" was based on the real life of Chris Sizemore, and "Sybil" (1976) ostensibly told the story of Shirley Mason -- but like most media images, these portrayals are only partly true, dramatized for effect.
Dissociative personality disorder can lead to extreme behavior, but it is seldom so outwardly stunning. Symptoms associated with DID include profound memory loss and confusion, hearing voices, substance abuse, compulsive behavior, panic attacks, suicidal thoughts and actions, insomnia and depression. Most people who suffer from the illness had previously been diagnosed with one or more different disorders, and they go years, perhaps decades, before discovering they have alternate personalities.
Next, myth 4: "DID isn't caused by trauma, because not all trauma survivors have DID."