There are very few studies done on stuttering, true, but of the studies done so far, the evidence points to a neurological difference in the brains of stutterers. On a balance of probabilities, this is likely the case for many, if not most, stutterers. Not sure what’s so offensive about pointing this out. Also, by denying a legitimate neuro/biological component to stuttering, we risk adding fuel to the pervasive myths out there that claim stuttering is caused by nothing more than a character flaw (e.g. nervousness, shyness, low self-confidence, etc...) and that a stutterer can cure their condition if only they “tried hard enough”, which is certainly not true for many stutterers.