https://pmc.ncbi.nlm.nih.gov/articles/PMC6997432/ ^^For developmental stuttering in particular Gives an idea as to how complicated it is! Stress can definitely increase the likelihood/frequency of stuttering in some PWS, but it’s important to know it’s not the root cause, as we’re finding there is a very definable physical cause. (definable, but not treatable with current technology—stopping here before getting into the ethical issues of whether a stutter should be treated).