For some people, it's best for their mental health to know they have the gene for Huntington's and some time in the future they'll have a problem. But to other people, it would be a disaster.
Medicine will be personalized and preventive: Your genome might predict that you have an 80 percent chance of breast cancer by the time you are 50, but if you take a preventive drug starting when you are 40, the chance will drop to 2 percent.