Stuttertalk.com is a fantastic podcast primarily for people who stutters, but they also have episodes about things like "what causes stuttering" or "what you wish people knew...", Im sure if you searched around you can find some helpful episodes to listen to on your work commute. Stuttering is not psychological in nature and is not caused by trauma or anxiety or anything like that. It's a neuromotor communication disorder. Stuttering is a result of a miscoordination between the brain and the muscles the produce speech (SLPs feel free to correct me if I'm mistaken). We don't know of exactly what causes it but we know there is a significant genetic component (i.e. It runs in families). I'm glad you want to learn more about him, I think that'd really great. Regarding the one example you gave, how do you think he would feel if he thought his wife thought she needed to do routine tasks like calling the landlord because of his stutter?