Mild stuttering may be a form of general stress release.  For whatever reason, most likely at a young age, a prolonged period of stress perhaps amplifies that mild stutter.  Some people show stress by fidgeting and some by blushing red and there’s obviously other manifestations to add.  Perhaps those with a mild stutter, and in a period of prolonged stress, start to show that stress with extreme stuttering. Once that extreme stuttering is commonly acknowledged then unfortunately it becomes the new source of stress.  There then starts a viscious cycle. I can’t recall properly when I first started stuttering, but I do know that in my teens it was my nemesis.  At school and knowing you were next in line to speak to the entire class, would feel like being slowly carted to the guillotine.  Sure, classmates may say beforehand they’re nervous, but you’d observe on their turn that they don’t exhibit extreme stuttering.  Why don’t they?  Is it because they’re busy fidgeting or blushing as they speak, allowing themselves to release that stress instead?  While those manifestations don’t interfere with their verbal message, unfortunately stuttering does. So, perhaps it’s just bad luck that we’re one of the ones whose bodies are built to handle stress by stuttering in a world built on communication. I don’t know really!