Most of the hopes and fears about genetic testing are based on a mistaken idea, not of what it does, but of what genes do.
Basically, identifying “the gene for” is nothing else than finding an statistical correlation between a chemical pattern in DNA and a characteristic in the organism. It doesn’t guarantee that the characteristic will be present, explain how it works, or — if the characteristic is an unwanted one — provide a cure. It’s a very useful first step on the path of figuring something out, but it’s usually very far from an explanation or an applicable technology. Gene tests rarely tell you anything that medical checkups and your family history won’t.
The current explosion of interest in genetic testing is similar to the frenzy of biological cataloging that often follows the exploration of a poorly-known territory. Sequencing technologies are becoming exceedingly cheap, and, together with semi-automated analysis algorithms, they provide “low hanging fruit” for scientific research. But it yields at best clues for further research into biological mechanisms; it’s more a tool for theoretical biology than for medicine.
It’s not likely for genetic testing to ever become a widely used diagnostic tool, as right now it only provides poorly understood correlations between genetic patterns and biological conditions, and once we understand the mechanism that goes from genes to biological (dis)function, we are much more likely to want to observe the organism itself. Blueprints are useful for understanding machines, but good engineers will always give precedence to what’s going on in the actual machine. Of course, organisms are interesting in that changing their blueprint actually changes them as well — cells are constantly interacting with their genetic material — so a finer understanding of biomolecular machinery is likely to provide us with treatment options radically different from the drug-based paradigm.
As far as privacy goes, genetic testing should be a non-issue, or at most at par with any other medical exam. The most comprehensive genetic tests available today give much less information than a routine medical checkup. For that matter, anybody seeing what you eat for lunch already has very good clues about your general and future state of health.
The danger of genetic testing lies not in what it reveals, but in what we believe it reveals. It’s not a pseudocience, but by being over-hyped and over-demonized, it’s at risk of being used for economic and social discrimination, just as unscientific disciplines like phrenology and “racial studies” once were. Politically, it’s irrelevant that genetic testing doesn’t really give any particular new insight into a person’s biology and future: unless this fact is widely accepted, there will be many attempts to use this technology to justify things in a rhetorical, not a scientific, sense.
This is not to say that genetic testing should be banned. That’s definitely not the case, specially when it comes to voluntary genetic testing. Even living in societies with often insane ideas about what you can and cannot know (particularly if you happen to keep a good part of your memory in digital media), it’s difficult to argue in favor of keeping people from knowing whatever can be known about their own bodies. But it’s important to be explicit, at the levels of both individual education and political discourse, about what a genetic test says — and what it