I experience this too, and I believe I understand the reasons, though knowing them hasn't made it much easier to overcome. It's all about confidence. With most of my family, I rarely stutter but my father is a different story. When I was young and would stutter, he'd mock me whenever he was irritated so very frequently. My mother did this as well, but my father took it further, even calling me "the stutter." His "advice" was unhelpful: "don't stutter!". Now, even as an adult, I can see him watching my mouth when we talk, waiting for me to stutter, though he no longer mentions it. Ironically, he's the person I stutter with most. There's another pattern I've noticed: I tend to stutter around people who I believe already know I stutter. If I stutter or block during an important meeting with colleagues, I'll prepare extensively for our next interaction, determined to prove it was just a one-time thing. Yet despite my preparation, I almost inevitably stutter again. Now, if I make a good first impression without stuttering, I rarely if ever stutter with those same people afterward. But if someone who's heard me stutter joins a conversation with people who haven't, I'll start stuttering again, as if their presence alone triggers the expectation that I will. It's strange, right ? Also when I'm alone, I never stutter or block. The same with my wife and children. I believe it comes down to anxiety and pressure when I sense that someone is judging me or has a negative perception of me, that's when the stuttering begins. Or I hate those times when I have to engage with a person for the first time, like going to the shop and asking for something to someone: those are probably the moment I would stutter 30% of the times, because feeling the eyes on those new persons on me triggers something inside me, like being vulnerable to their judgment.