I developed a stammer around age 27 (5 years ago) and I think it was stress induced from my job at the time. I left the job and have low stress. The stammer essentially went away but still pops into my speech once in a while. When it was really bad I went to a session with a speech therapist. I aced her tests and she said I didn't have a stammer so I never went back although it still affected my life.