Sadly in India back in early 2000's, I suffered much in college due to this. Professor even asked me why can't you rectify your stutter. Explaining the experiments was really hard and my team mates get 9/10 and I get 5/10 or 6/10 max. Even bunked the classes as I can't tell attendance in many classes. Later I openly went and told to staff , if I raise my hand ,please please check mark my attendance that I am present for your class. Now fast forward , my stubborn mindset kept my life running ,now at 42 ,I no longer care for stutter being a software programmer, not much talking. If your son is young and still studying at school , you can make him interact with public and give him motivation and support him till the end of your life. Lot times caring parents can make their stutterer kids as better achievers in life. Good luck!