Stuttering does not affect intelligence.There is no link between intelligence and stuttering. A child who stutters is no less intelligent then a child who doesn't.
Anxiety and stress do not cause stuttering. Stuttering is most likely caused by a difficulty with neural processing (brain activity). A child who is predisposed to stuttering, may stutter more when they are placed in a situation that causes stress or anxiety.
Parents do not cause a child to stutter. As a parent it is always easy to feel guilt for a child's difficulty. However, parenting skills do not impact on a child's stutter. If you have concerns for your child's speech and feel they may be stuttering, then it is recommended that you see a Speech Therapist. Every child is different, and every child needs to be seen individually by a Speech Therapist to assess their skills.
Stuttering can be treated. There are a number of therapy approaches that have been proven to have significant positive results in treating stuttering.
Will my child grow out of stuttering? Sometimes, but not always. Unfortunately it is difficult to predict who will grow out of stuttering and who won't. A test by a Speech Therapist will look at a number of factors that are relevant to you and your child. Recommendations about whether to start therapy will be made based on these factors.