"Nobody was to blame"
His father says that to his son about his youngest son's death. Err yeah, you were to blame. You stupidly walked on ahead and let your youngest trail at the back, thereby not being able to keep an eye on him. As a parent you wouldn't even do that in a park on a normal day but these guys did it in an environment with human-killing monsters about where silence is imperative.
Most irresponsible parents ever. It's amazing they even survived so long.