At this point, the cause of autism remains unknown. However, one theory that has strong scientific evidence is that genetics play a significant role in contributing to the occurrence of ASD. Studies show the concordance rate for identical twins is much higher than for fraternal twins, and ongoing research is beginning to identify genes that may put an individual at risk.

Additionally, in the last decade, we have seen considerable speculation about environmental toxins, diets, and vaccines, but there is no convincing scientific evidence that demonstrates a causal link to ASD. In particular, there is overwhelming evidence that vaccines do not cause ASD. As a result, adherence to these speculative beliefs is tragic because children are harmed by not receiving life-saving vaccination.

Finding the answer will require long-term, painstaking, rigorous, and sophisticated scientific investigation. Professional responsibility and ethics demand that care be taken not to over-speculate, misrepresent nor present mere hypotheses as facts for the causes of autism.