I am not sure if stuttering comes From anxiety/shyness - I think it CAN be, but observing my 9 year old kid who stutters, I don’t think always. He is a super-confident chatterbox who barely notices that he stutters. For him, I think there is some kind of brain to mouth wiring that just doesn’t work quite as intended. I have seen huge improvements for him in his fluency through speech class and actively using the techniques he learns there, so from that perspective I’d say yes - it’s something that can and should be taught!