Honestly, it sounds like your parents might need to be educated about stuttering. I would suggest gathering some material to present to them. They need to understand that stuttering is a legitimate disability that may or may not improve, even with years of speech therapy. With that being said, I think it's also important to point out to them that, while people who stutter may need to navigate through life in a different way, we're no less capable of living successful, productive lives.