[zekenie]

But often people get certain tests when they have certain symptoms or risk factors. For example, smokers are much more likely to have lung cancer. Screening them for lung cancer is a good idea, even if the screen has some false positives because there's a reason why the the group has above average risk for the disease.

People are screened for the BRCA gene when they have a history of certain cancers in their family. If you get a positive result, there's a small chance its wrong. But, if you took all of American and gave them that test, there'd be thousands of people getting positive results, living in fear, and sometimes taking medical action.