The absence of kid-zombies from State of Decay never rankled me; in my narrative they were evacuated from Trumbull Valley within hours of the outbreak. It's a plausible explanation. Believable explanations aside, though, it's also understood by us SoD vets that UL made the artistic choice not to include undead children as cannon fodder. One needn't stretch one's brain too far to understand why. Who wants to dispatch kids (even if they're zombie kids) with a rifle or a knife? Not me. Not especially. That said, I think it's a perfectly legitimate question (given the nature and extent of the outbreak), particularly when it's asked by newcomers to the franchise.