This is really interesting. Stuttering in a child that is attributed to copying the defensive-protection mechanism from a stuttering parent, and thus, using stuttering (or disrupting initiation of speech motor plans) as a protective behavior. If you phrase it like that, it makes sense. Research should investigate this further. From what I have read, research does indicate that there needs to be more investigation into environmental (or epigenetic) factors contributing to early onset. For example, they could research if stuttering recovery in children occurs more often when a child lives separately from their stuttering parent versus living together with them (which can indicate the extent to which epigenetic factors contribute to stuttering recovery versus persistence).