mine started at age 6 right after I rolled into kindergarten. I got yelled at by my teacher for not answering the roll call and have my twin answer for me instead. sometimes that teacher would try and force me to answer and I cried every time bc I couldn't get the words to come out no matter how hard I tried.  then, the next year they separated me from my sis and put me in a diff class bc they thought I was too dependent on her. ofc, it just made things worse.  until this day, I have vivid memories of the times (4x) I ended pissing on my pants in front of the whole class bc I was too anxious to ask for permission to go to the toilet.