I believe they go hand in hand. Instead of having anxiety or fear when talking to your sister, maybe you have anxiety or fear over specific words (even subconsciously knowing you’re going to stutter on those words). Some say that the fear of stuttering perpetuated stuttering. For me, my heart beat rises and I get anxious/sweaty whenever or wherever I am when I know a block is coming. Not when I stutter, when I know it’s coming on a specific word.