It's often meaningless to talk about a genetic trait without also discussing the environment in which that trait appears. Sometimes, genes don't work at all until the environment awakens them.

The more that I looked at DNA, the more I realized it was nature and nurture. It's how genes and your environment work together to produce the person you are.

Genes work with probabilities; they don't work with certainties. So most things that you're looking at with these genetic tests, it's not like you're condemned to automatically get the disease or the syndrome. There's a lot of factors in play there.

Things look especially bleak for common killers such as diabetes and heart disease. Those ailments clearly have a genetic component. But when scientists survey genes looking for which mutations patients have in common, they come up empty.

Genes are like the story, and DNA is the language that the story is written in.

In 'The Violinist's Thumb,' I talk about the poignancy of cells leaking across the placenta into both the mother and the child.