Autists have emotional responses as strong as, or perhaps stronger than, most "neurotypicals ", though what generates an emotional response might not always be the same. What they lack is the inborn ability to express their emotional state via body language, facial expression, and nuance in the way that most neurotypicals do. Autistics who speak, those who don't.

Autistic Disorder, in my view, should more properly be called the "group of Autistic Disorders" rather than be viewed as if Autistic Disorder is a single entity with a single cause, course and outcome. Just as "mental retardation" is not a single entity? There are many sub-groups with differing causes?Autistic Disorder, or autism, likewise is not a single disorder with a single cause in all cases.
What You Should Know About Autism Spectrum Disorders. Signs, Symptoms, Treatments and Effects on Daily Life