"Adam was not open to therapy,” Peter Lanza said. “He did not want to talk about problems and didn’t even admit he had Asperger’s.”
But Peter Lanza said the Asperger’s diagnosis might have distracted the parents from other possible problems, including schizophrenia. “Asperger’s makes people unusual, but it doesn’t make people like this,” he said. “I was thinking it could mask schizophrenia.”
“If he had been a totally normal adolescent and he was well adjusted and then all of a sudden went into isolation, alarms would go off,” he said. “But let’s keep in mind that you expect Adam to be weird.”
Here's the quote from The New Yorker interview.