What condition provided significant support for the genetic contribution to autism spectrum disorder?

The significant support for the genetic contribution to autism spectrum disorder is highlighted by the higher incidence of autism in monozygotic twins. Research shows that when one identical twin has autism, the likelihood that the other twin will also have autism is significantly higher compared to fraternal twins. This suggests a strong genetic link because monozygotic twins share nearly all of their genetic material, while dizygotic twins share about half.

While mentioning concordance among dizygotic twins being 10% indicates that factors other than genetics, such as environmental influences, may also play a role, it is the higher rates of concordance in monozygotic twins that strongly underlines the genetic component of autism. Thus, the evidence of higher prevalence in identical twins compared to non-identical twins directly supports the idea that genetics significantly contribute to the development of autism spectrum disorder. This finding continues to drive research into the specific genes and genetic mechanisms involved in autism.