Not necessarily!
This is a popular misconception. In fact, there is exactly the same spread of personality types amongst those who stammer as in the whole population.
It is worth bearing in mind, though, that it is clear that the more anxious any speaker is, the less fluent they may become - this is especially true for many people who stammer.
And, unfortunately, stammering is often portrayed in this way by the media and in literature. Even in 'Harry Potter' books there are several references to characters "stammering nervously". And the first question that we are asked by journalists is often: "Is stammering caused by nervousness?"
Stammering can affect a person's confidence in some speaking situations and as a result the individual may seem to be more reticent or reserved. This has probably developed because of the unhelpful reactions of others to the stammer - based on misconceptions and a lack of understanding.
