Non-autistic children learn the social rules by watching others. With autistic children, they have to be taught these rules directly. This can be a long process. Not all the behavior they display is because of an act of will. Children with autism do not smile.
Autistic children can and do smile, laugh, and can be extremely happy.
Children with autism do not want friends. In the example with my three children, my oldest, Michael, is content to be by himself a lot, who has some friends, but feels little need to socialize with them. Whereas his sister, Renee, has a strong desire to have friends, and this is very important to her. Also, my youngest, Nathaniel, though starting and maintaining friendships are difficult for him at times, having friends are important to him. Autism is a neurological disorder that affects the functioning of the brain.