Stuttering is unique to each individual. The causes are myriad and tailored to each person. It sometimes goes away after a short time or it might stick around for life. It might be mild or severe or vary between the two. But like anything, there's countless ways of dealing with it. Speech therapy is a great idea. It's also important to not frighten your son with too much concern. Yes it's something new and different to get used to. You might want to point out some of the other people who stutter who have done well. The current president of the United States is a stutterer. The actor who does the voice of Darth Vader is a stutterer. There are many others of stutterers who have done well despite struggling to speak. You might remind your son how he struggled to walk when he was small. He probably fell over many times and got frustrated. But eventually he figured it out. He will also figure out ways to communicate no matter the obstacles. And we are all unique people with unique attributes. Think of how boring the world would be if we all spoke the same. I've stuttered my whole life but am quite content. I'm proud of the unique way I form words and phrases. It's what makes me, me. Your son will be the same no matter what his fluency.