it. this is really significant. it means environment plays a bigger role. it plays twice the role of a factor in this disorder. alisyn: i guess the way they figured that out is they figured out the fraternal twins also have a higher incidence of autism, that means is must be something happening in utero or at birth. >> they saw that there was, know, an increased risk that it musting something in the prenatal environment or something that is affecting the expression of the mother's genes. alisyn: does this lend credence to the theory that many parents of children with autism hold, and that is that there is some pollutant or medication that happens and interrupts the regular development. >> the fact we've gone from one