Why is it that my stuttering increases when I’m home?

Why is it that my stuttering increases when I’m home? I’ve had a stuttering problem since I started talking as a child. It has lessened greatly since growing up and also quitting drinking. I am quite introverted and spend most of my free time alone. I have no conscious social anxieties outside the average range for a fully functioning human person. Still, you would think that if it varied at all, it would increase when I am out in the world. But instead it spikes when I am home, where I feel most comfortable. I live with one family member who I get along with perfectly. Why?? Does this happen to anyone else?