No two individuals are alike. Some people are genetically predisposed to develop asthma, whereas others can cheerfully live a hundred meters from a major highway with no adverse effects. Genetic predisposition also plays an important part in the efficacy of drugs and in the progress of diseases like cancer, heart failure, and diabetes. Individual differences make doctors’ work more difficult. They can never be sure precisely how susceptible a person is to a specific disease or how effective a particular medicine will be. We can measure all sorts of things, but what do we have to know before we can accurately predict whether a given person will fall ill? Part of the answer is hidden in our genome: Inherited defects and sensitivity to medication show up in our DNA. The map of the human genome was colored in at record speed at the beginning of this century by two rival research teams, which ended up publishing their results simultaneously in 2001. Their achievement was compared with the first moon landing and the invention of the wheel. One of the competing groups was headed by American Craig Venter, who continues to spread the DNA gospel enthusiastically. Initially, Venter was part of the U.S. government–sponsored Human Genome Project, but he left the group. He founded a private company to create a database of genomic data. Venter characteristically mapped his own DNA, revealing that he bears a heightened risk of alcoholism, coronary artery disease, obesity, Alzheimer’s disease, antisocial behavior, and conduct disorder. Unfazed, he enthusiastically published his complete genome on the Internet. “A lot of people are scared to have their DNA examined,” he says. “They think all their inner secrets will be revealed. Even medical students are wary about supplying their DNA. But the course of our lives isn’t genetically determined, apart from exceptional cases where life expectancy is reduced by a serious hereditary condition.” Most people aren’t aware of the subtle mechanisms of genetics, he adds. “People think like 1980s scientists. Possibilities for analyzing DNA were limited back then.