He’s a fascinating case, indeed. However, I’m skeptical that his mother was as bad as Ed says she was. How “paranoid” was she, really, of a son who actually tortured and killed animals? Maybe she could have handled it better, but I think she knew something was deeply wrong with him, and was afraid for herself and her daughters.
It wasn’t until after he was incarcerated for killing his grandparents that the “my mother made me this way” story got started. He originally said he killed his grandmother just to see how it would feel.
While he was in the psychiatric hospital for that, he was allowed to help the psychiatrists to administer and file tests. He would have seen a lot of the tests, as well as the prevailing theory that evil mothers are what made boys go crazy. It just seems like he found a good excuse for his own pathology, one that allowed him to blame someone else (of course).