I’m 41, I had speech therapy as a kid and it pretty much went away. Didn’t really have issues through school. Started a job, and my manager had a bad stutter, and it brought mine back, and I tried really hard to not stutter, incase he thought I was taking the p*ss, which made it worse. Then I managed to get it largely under control, then it recently started up again quite badly, I ended up having to leave my telephone based job because of it.