"The causes of autism are still being looked into. Many experts believe that there isn't one specific 'cause', and that there are genetic factors. We are always looking to understand more about autism, and welcome any research in this area."
https://www.autism.org.uk/advice-and-guidance/what-is-autism/the-causes-of-autism
Causes
There is strong evidence to suggest that autism can be caused by a variety of physical factors, all of which affect brain development – it is not due to emotional deprivation or the way a person has been brought up. Evidence suggests that autism may be genetic. Scientists have been attempting to identify which genes might be implicated in autism for some years. Autism is likely to have multiple genes responsible rather than a single gene.
https://www.autism.org.uk/advice-and-guidance/what-is-autism/the-causes-of-autism
Vaccines
There is no link between autism and vaccines. So how did the idea that vaccines play a role get started? Much of the blame lies with a study published in 1998 that suggested that the MMR (measles-mumps-rubella) vaccine, or infection with the naturally occurring measles virus itself, might cause autism. Since then, numerous scientific studies have shown that there is no link between vaccines — or any of their ingredients — and autism. And the research used in that study was found to be false, the doctor who wrote it lost his medical license, and the medical journal that published it retracted the paper.
