The United States' Genetic Information Non-Discrimination Act takes effect on Saturday. Subsequently, it will be illegal for employers to use genetic test results to make decisions about their employees, or even to gather genetic information on people. That includes family histories of heart trouble, stroke, and other common maladies—which means that businesses' frequently-used "health risk" assessment forms will have to lose their intrusive questions about people's ancestors and relatives.

These new protections acknowledge that there are people whose genes might put them at a disadvantage compared to others with run-of-the-mill DNA. What about the opposite case, though? What happens if there are a few people who have a genetic advantage relative to the rest of us, because they have been artificially enhanced? (Don't assume they're in the same position as people who are naturally gifted. Today, you can't identify a genius musician with a DNA test; you have to listen to people playing their instruments. But if, in the future, there are people with a gene supposed—rightly or wrongly—to be good for music, then it will be possible to pick them out by a blood test.)

It's widely assumed that this kind of enhancement will soon be possible. And this fall researchers announced what might be another step in that direction: By genetically manipulating a rat embryo, they created a rodent whose NR2B gene is far more active than normal. That gene codes for a protein involved in the kind of communication in brain cells that's associated with learning and memory. Result: A rat that's much better than normal at learning things and remembering them.

Biotech companies are interested in this research in part because memory-enhancing treatments could stave off the effects of Alzheimers disease and other forms of memory loss. But once a treatment is around for impaired people, "off-label" uses will pop up faster than you can say "Adderall." For a serious consideration of the ethical quandaries that brings up, this is the book. If you have less time, there's always the splendidly creepy Gattaca, about a world divided between genetically enhanced elites and mongrels made the old-fashioned way. Which, by the way, looks set to become a TV series in a couple of years.