Between 5% and 15% of children stutter at some point in childhood. These are 'normal dysfluencies' of the growing child. Many children recover spontaneously. Some children may persist with this manner of speaking due to certain stress in the environment - birth of a sibling or
other stresses of the early family life. This stress could also be due to demands made by “Grammar”, which a child is just beginning to learn at this stage. Genetics also play a role, since about half of such children may have a PWS as a close relative. The sex ratio among children who stammer is equal but gradually becomes 4 men to 1 woman in the adult age population.

“I invariably gave wrong answer in the class. This was preferable to giving the right answer and stammer..” (an Indian PWS).

Over all, about 1% adults are expected to be PWS. They can be found in any caste, community, ethnic group or region. Therefore their number in India would be at least one crore (i.e. ten million). Some Indian therapists claim that their number could even be more- almost 3%. But due to cultural stigma and social attitudes, they may neither seek help nor accept their problem openly.