I believe it’s a neurological condition that is highly sensitive to emotions. I think of it as having more than average trouble sequencing lips, tongue, vocal cords, and lungs for speech. So add stressors and there is breakdown due to avoidance anxiety. It’s almost like walking a balance beam. Most people walk say a 2 ft wide beam. A stutterer might walk a 4 inch wide beam. Add anxiety, fear, fatigue, and anyone can fall off? It runs in families….