I am a severe stutter and my father is a mild stutterer. One of the therapist told me that possibly I've started stuttering cause i was missing my father (at the years of start speaking my parents were appart). I always thinked thats she was wrong, that she sayed this as a corny explanation to confort me. Now I see that maybe it's true. However the study only includes 3 couples and sons, so it's very limited.