Since Killer Kane was Maxwell Kane's father, Max was worried that he, too, may suffer from the same malady. Kane was a violent man who, we find late in the story, strangled Max's mother right before his eyes when he was a young child. Max's suffered from very low self esteem, in part from the knowledge of his father's past, and since he was told that he looked just like his father--as well as inheriting his huge size--Max was afraid that other aspects of his father would also be passed on. His grandfather, Grim, was also worried about these aspects, since Max showed signs of anti-social behavior before teaming up with Freak.