I stutter when talking to my parents, but never with friends, speaking in public etc

I stutter when talking to my parents, but never with friends, speaking in public etc As the title states, I stutter quite badly when talking with my parents but never with wider family, never with my friends, never with my partner, never in any sort of public speaking/speaking aloud. I know this is probably the complete opposite of what many people experience, but does anyone know why? (Before you ask, I’ve always had a close relationship with both parents, have never been abused, rarely shouted at in 22 years etc).