I wasn’t particularly asking for an explanation of the mechanisms behind stuttering, but more so inquiring whether the incidence of a person’s stutter is genetic or related to outside factors. Myself, for example, stuttering is genetic on my mom’s side, but is definitely exacerbated in situations that are stressful. I’ve only met one other person who had a speech impediment, and it was milder and brought on by stressful situations (didn’t happen chronically). Thanks for the reply, though!