It’s all speculation the science doesn’t have answers either so it’s all theories at the end of the day and idk the author of that book I’m assuming you looked them up and found out they do not stutter/are not an SLP? Even if they aren’t if OP saying their stutters stems from some of those reasonings it’s not speculation it’s ones own personal experience therefore they’re not wrong from starting a conversation around the topic. Now if the book says “this is exactly why you stutter or have anxiety” then yes I’m all for debunking that’ll be faux information and shouldn’t be spread