Final answer:
The primary risk factors for autism are not fully known, but genetic and potential environmental factors may contribute, while vaccines are not associated with ASD. Improved awareness and diagnostic standards are reasons for increases in ASD diagnosis rates.
Step-by-step explanation:
The highest risk for contracting autism, a complex neurodevelopmental disorder, is not fully understood, but a combination of genetic predispositions and environmental factors are implicated. Current understanding is that there is no single cause but rather a multitude of factors that may contribute to the development of autism spectrum disorder (ASD). Genetic factors play a crucial role, as evident in conditions such as Fragile X and Rett's Syndrome. However, for most cases, it's likely that multiple gene mutations are involved. Environmental factors may influence the development of ASD but determining these factors is challenging. It is important to note that vaccines have been extensively studied and found not to be associated with an increased risk of autism. The increase in diagnosis rates may be due to several factors including improved awareness and broader diagnostic criteria.