I have heard that but it was from a person and not a book.  I am a 65 year old female who has stammered/stuttered all my life. I was made fun of and called names. I recall my  6th grade teacher mimicked me and made me cry.  I have taken  a few IQ tests and scored much higher than I had assumed. It was a relief! Thank you for your post. Just because we can't get it out doesn't mean we don't know it. BTW, my speech highly improved as I aged.