Misunderstanding the Genome: A (Polite) Rant

A recent Ars feature story about genetic screening generated quite a lively debate in the discussion thread. However, it also underlined just how many misconceptions people have when it comes to genetics. Public perception hasn't been helped by scientists overhyping their findings or by inaccurate portrayals in the media (GATTACA, anyone?). So today, I'm going to try to clear some common confusions.

Before moving recently to Ars full time, I spent six years working in the policy office of the National Human Genome Research Institute, the part of the National Institutes of Health responsible for the Human Genome Project (along with the UK's Wellcome Trust). The job gave me a front row seat to the challenge of explaining a horribly complex topic, one where common assumptions are often counterfactual.

Maria Delany's Ars article does a great job laying out how screening at-risk individuals for mutations in a pair of genes—BRCA1 and BRCA2—can spare people from developing cancer. Delany also explains why there isn't unanimity among clinicians about rolling out BRCA testing at the population level. At first glance, such...