Can there possibly be environmental factors that contribute to autism or spectrum disorders? Recent research suggests this may be the case.   A study published November 2010 in Archives of General Psychiatry researched 192 identical and fraternal twins where at least one twin had classic autism, and in many other cases the sibling had a less severe form of autism or autism spectrum disorder. It is important to note that identical twins share 100% of genes where fraternal twins share 50% of genes.   Comparing identical and fraternal twins allowed the researchers to not only measure genes but also the role of environmental causes.   In this study 77% of identical male twins and 50% of female identical twins had autism or autism spectrum disorder compared to 31% of male fraternal twins and 36% of female fraternal twins.   When reviewing the results above, mathematics and statistics concluded that 38% of autism or autism spectrum disorder attributed to genes and 58%...