Burgeoning cases of autism are strongly linked to the environment, researchers have discovered. A study of twins indicates that while genetics plays a role, the environment is a more significant factor. The study used results among both identical and fraternal twins, and a mathematical formula that determined that genetics accounts for a 38% risk of autism, while environment factors account for 62%, reports the San Francisco Chronicle. "We've known that genetics played a huge role. The surprise was that the environmental factors have been underestimated," said spokeswoman for a patient advocacy group that participated in the California study.
Which environmental factors trigger the disorder is a mystery, though at least one researcher indicated the focus may now shift significantly to prenatal conditions for developing fetuses. Another new study, for example, has found that autism rates are higher among children of mothers taking anti-depressants during pregnancy. "We're just beginning to scratch the surface," said an autism expert in Oakland. "We have to continue to look at genetic factors," she said. "But it's really important to look at non-genetic factors, too—and critical to look at them together."