According to research, not all stuttering is genetic, however family, twin, and segregation studies overwhelmingly support a strong genetic influence on stuttering risk (e.g., see [this](https://www.sciencedirect.com/science/article/pii/S2666247721000543) research). "*There is now strong evidence that almost half of all children who stutter have a family member who stutters. The risk that the child is actually stuttering instead of just having normal disfluencies increases if that family member is still stuttering. There is less risk if the family member outgrew stuttering as a child.*" ([source](https://www.stutteringhelp.org/prevalence))