It is apparent from the beginning of the novel that Christopher Boone has a variety of behavioural problems. His condition, despite creating an immense mathematical and logical intelligence, causes him behavioural problems that are often hard not only for himself to deal with, but also his parents. Christopher himself finds it easy to pinpoint these problems expressing that he doesn't like "being touched", "not liking yellow things or brown things and refusing to touch yellow things or brown things" and "groaning". Christopher's behavioural problems placed stress on both of his parents, most notably his mother who left him, as she was not able to deal with him being "different". Christopher's problems required the special attention of his father who has to cook his meals which involve his many eating habits, wash his clothes, look after him on weekends and when he gets sick or into trouble. Christopher's behavioural problems are seemingly what broke up his parents' marriage as they both had different opinions about to deal with them.
Judy Boone, Christopher's mother, indeed showed that she has behavioural problems of her own such as a short temper, pessimism, and acting on sudden impulses which led to her abandoning her son. She was short-tempered and suffered from depression, which was part of the reason she decided to leave as she felt that Christopher "didn't really need [her] anymore". She