The letters A, T, G and C, which represent different DNA bases, spell out the blueprint for the human body. But they aren’t the only ones that matter. CH3 is the chemical formula for a methyl group — a carbon atom studded with three hydrogens. Methyl groups can attach to DNA and affect whether the DNA is recognized by the cell’s machinery. Different exposures and experiences — anything from air pollution exposure to stress — can make DNA more or less likely to gain or lose methyl tags.

I’m trained as a geneticist, but I suspect that genes are not the whole story when it comes to autism.  More and more scientific evidence suggests that environmental influences are contributing to increasing rates of autism.

Many researchers tend to put genes and environment in separate boxes and study them separately. But others of us have come to realize that the genome does not exist in a lockbox away from environmental influences.