Must of been a tension filled, stressed out childhood. http://www.fluencyenhancer.com/model_stuttering.html
When individuals are under stress they get tense. The tension can be measured. Electrodes can be attached to the muscles and sent to an appropriate measuring instrument. When this has been done in the past, it has been observed that some people get more tense than others and that everyone seems to have a spot on the body where they focus their tension. This spot is called the Target Area. People are born with it, and sometimes it is inherited.
The five most common Target Areas for people are the muscles of the shoulders, the abdominal wall, the face, the hands, and the lower back. Most people, under conditions of stress, tend to focus tension at one of these five areas. But in addition to these, there are a group of other Targets, affecting small percentages of people.
One of these, affecting two and a half percent of the people in the world, are the muscles in and around the vocal cords.
It is our contention, derived from the results of many studies, that all people who stutter come from this two and a half percent subpopulation. In other words, people who stutter are born with a Target Area at their vocal cords; people who stutter are born with the tendency to get "all choked up" when under conditions of stress.
As they get older the original stresses disappear. They are replaced with new stresses. There are three particular stresses that people who stutter suffer from: feared sounds, feared words, and feared speaking situations - and now, in response to these stresses, they lock their vocal cords and fire off their stutter reflex. Or, instead of letting that happen, they learn to substitute easy-to-say words for difficult ones, or learn to use starters to get their vocal cords vibrating, or remain silent, or learn simply to avoid difficult speaking situations altogether.