Not quite.  
Here is a summary of that same study
//www.autismspeaks.org/node/10901

To quote (not the first sentence):
"In other words, we now have strong evidence that, on top of genetic heritability, a shared prenatal environment may have a greater than previously realized role in the development of autism in twins."

It is true that the study found evidence for some environmental connections, but the evidence is not conclusive.  Also, studies since then (in the last 5-10 years) are zeroing in closer on an apparent strong connection to genes and physical development of brain tissue.