On the front of its Personal Journal section, the Wall Street Journal (9/25, D1, Beck, Subscription Publication) reported that according to experts, autism appears to have both genetic and environmental causes. For example, a study of 192 pairs of twins with an autism spectrum disorder revealed that even when one identical twin has autism, the other twin has a 70% chance of also having autism. Among fraternal twins, the likelihood of the second twin being diagnosed with an ASD is about 35%. Both the Autism Genetic Resource Exchange and the Autism Sequencing Consortium are working with DNA samples to identify genes related to autism. Other factors that may contribute to autism are advanced paternal age, being born prematurely, and poor maternal nutrition during pregnancy.
— “Progress in Identifying the Genetic Roots of Autism, “Melinda Beck, The Wall Street Journal, September 24, 2012.