Scientists aren’t certain what causes autism, but it’s likely that both genetics and environment play a role.    Researchers have identified a number of genes associated with the disorder.  Studies of people with autism have found irregularities in several regions of the brain.  Other studies suggest that people with autism have abnormal levels of serotonin or other neurotransmitters in the brain.  These abnormalities suggest that autism could result from the disruption of normal brain development early in fetal development caused by defects in genes that control brain growth and that regulate how neurons communicate with each other.  While these findings are intriguing, they are preliminary and require further study.  The theory that parental practices are responsible for autism has now been disproved. In February 2009 a special federal court ruled that there was no proven link between certain early childhood vaccines and autism that developed in three children. Many other studies, including by the National Academy of Sciences, have shown that there is no link between childhood vaccination and autism.