It would be more interesting if it was his brain tumor that drove him to kill, and that by occupying his body Ee Jae Chae is driven to kill too. But they've already established that he was evil as a kid, at which point he probably had no tumor. Missed opportunity
It's not his mom's fault that Gosha passed on his sickening genes to her. I think she was totally justified in not wanting to live deformed and misshapen. Gosha having a wolf child is akin to two parents with AIDS having a child and passing it to them.