It's hard to measure trauma though. As Gabor Mate, a respected trauma researcher, says "Trauma isn't something that happens to you. It's what happens inside of you in response to something that happens to you" Neglect can have that effect. To me, John Harrison's theory is most convincing where he says stuttering is akin to a frozen response where you have a divided intention between your unconscious (does not want to speak because it's afraid of something -- like asserting oneself, revealing oneself, or rejection -- and so your body's speech muscles clenches up) and your conscious (wanting to speak). So the combination of these creates stuttering. It's like trying to pee in a public bathroom. You want to pee but for whatever you "cant". This isn't proven but given that we still don't know what causes stuttering, this is the most convincing theory I've found. The neurological theory is still unfounded - do we stutter because of our neurology or do we have a different neurology because we stutter..