There are a number of Myths about speech related disorders, here are a few:

Children with Autism never make eye-contact during interaction.
While some children do make eye-contact, other may take several months/years to learn the ability to make eye-contact.

Child suffering from Autism cannot show affection.
Although it may seem that way, it is not always true. It takes time, patience and a lot of hard work to establish a strong connection with an autistic child.

Being a bad parent can cause a child to become autistic.
This is a complete myth.

Autism is a rare disorder.
This is False; The United States Centers for Disease Control (CDC) estimate the prevalence of autism to be about 1 in every 150 children. In 2005, the National Institute of Mental Health (NIMH) estimated 1 in 1000. And in 2006, NIMH estimated that the incidence was 2-6 in every 1000 individuals.

Autistic children cannot learn.
This is false. The question is not if they can learn, but it is how they can be taught. Since every child is different from one another. Every child has to be taught differently and accordingly.

Autism is a disorder that can be out-grown over time.
This may sound good, however is not true. Autism can however be treated in almost every case.

Showing signs of affection means that your child does not have autism.
This is another myth. Children are all different, and with hard work, time and love, many children will eventually learn to show their emotions through smiles and other signs of affection.

A genius lies inside an individual with autism.
Children with autism usually have a very broad range of skills and may score high in their IQ test, however a child who may name every country in the world with their respectable capitals, may have trouble with the most simplest thing, like tying their own shoelaces.