I don’t specifically stutter on s’s. Also let me drop my 10 cents: I don’t think that looking for a relation in such sense is going to turn into a ‘theory’ on letters frequently stuttered from us. I guess we all agree on the fact that even though many of us have a stutterer as a close or far relative, it’s primarily something psychosomatic. I do stutter on social occasions regardless of the letter I’m saying.