Hi! Speech Language Pathologist here. Stuttering can absolutely be genetic, and it's more likely to occur in men/boys than women/girls, so I'm not surprised that you have a brother who stutters! Stuttering is not caused by nerves/anxiety, but communicative pressure can exacerbate it. Many people stutter less when talking to kids, animals, or friends compared to when they talk to authoritative figures. I sometimes have clients draw a communication ladder while we talk about who might be at the bottom of the ladder, the easiest audience to talk to, and who might be at the top of the ladder and which tools they might choose if they want to be more fluent when speaking in higher pressure situations. Any fluency/stuttering modification tool might or might not help, and what we know is that they are most helpful when they're novel - if you use them too much, (a) it's super fatiguing and annoying, and (b) they are less likely to work the more they are used. So my goal is to always suggest clients work on stuttering comfortably, rather than working on creating more fluent speech. Great questions!