Autism is a terrible disease with no known cure.
Do you know how many people are affected with it?
Not precisely, but  Autism is caused by both genetic and environmental factors.
how is it caused by enviromental factors?
Causes of autism
Many causes of autism have been proposed, but understanding of the theory of causation of autism and the other autism spectrum disorders (ASD) is incomplete. Research indicates that genetic factors predominate. The heritability of autism, however, is complex, and it is typically unclear which genes are involved. In rare cases, autism is associated with agents that cause birth defects. Many other causes have been proposed, such as childhood immunizations, but numerous epidemiological studies have shown no scientific evidence supporting any link between vaccinations
that is primarily inherited by men.
Height and intelligence may be correlated, but there is not significant proof of it being caused by genetics. There are many genes associated with genetic transmission of intelligence, but current theories of intelligence point to inheritance of intelligence from parents to be due to both genetic and environmental factors, especially as there is no concrete proof of the relationship between certain genes and intelligence.
The correlation between height and intelligence could also be confounded by how cultural and psychological factors affect the expression of intelligence.