Responding to a review of the recent movie The King’s Speech, a professor who struggled with stuttering quickly talks about the sociology of stuttering:

As a person who sometimes stutters and as the author of a doctoral dissertation (The Quest for Fluency, University of Toronto, 1977) and a half dozen or so publications on the sociology of stuttering, I was pleased to read the excellent articles by Tom Spears on the film The King’s Speech and on the stuttering management program at the Ottawa Regional Rehabilitation Centre. As scientists and speech therapists have noted, stuttering is a puzzling phenomenon, shaped by neurological and psychosocial factors, for which there is, technically speaking, no cure but which individuals can learn to manage successfully through a variety of strategies to achieve more relaxed, flowing speech. For some individuals, as they cease to struggle and become more comfortable in their own skin, stuttering may even virtually disappear as a problem; for others, neurological and psychosocial propensity may be so obdurate and self-defeating avoidance practices so stubbornly ingrained, that only strictly applied therapeutic speech techniques may provide modest improvements in fluency and comfort.

From this short letter, it sounds like anxiety and stigma can contribute to the issue of stuttering. Like many human concerns, a combination of individual and social factors can lead to challenges.