Hi, I plan to work on stuttering in grad school so I'll be putting that into my personal statement as well. Although I still haven't done it, I can give you my two cents from my experience during job interviews when I've disclosed that I'm a stutterer. Personal statements are supposed to make you stand out as a real person with experiences that make you who you are and I feel that it's the personal quirk of yours that they want to see. While writing about your stutter, you can tie it up to how you've grown with it, made it your own, how it has helped you become who you are and how it will help you in the future in becoming more empathetic or even making a difference. You can also try and tie it up to the discipline you're opting for and how you see yourself leaving your mark on that discipline as a stutterer, as a person with a unique kind of experience. I feel that you being confident and strident about your stutter in the statement will not give them any reason to hold it against you. Show them exactly why they shouldn't hold it against you. Good luck!