His parents, of course, have trouble relating to their son. The stress of trying to raise someone who thinks so very differently from them takes its toll, and manifests in outrageous, and yet realistic, ways. Although the entire story is told from Christopher's point of view, the emotion and intentions of the other characters come through to the reader, despite that Christopher himself cannot interpret this data in any meaningful way beyond the fact of what is said and what is happening.
It is interesting that Haddon himself has little to no experience with autism, or autistic children. In fact, he did very little research on the subject in writing the book. Those who live with or know autistic people may be a better judge, but I felt the book was true to what I understand of that particular mental-mode. Autism fascinates me, but I also agree with what Haddon wrote about the subject:
Labels say nothing about a person. They say only how the rest of us categorise that person. Good literature is always about peeling labels off. And treating real people with dignity is always about peeling the labels off. A diagnosis may lead to practical help. But genuinely understanding another human being involves talking and listening to them and finding out what makes them an individual, not what makes them part of a group.And that is the take-away from the novel as well.