Knowing a medical condition “runs in the family” has long informed physicians’ clinical diagnosis of patients’ symptoms. Today genetic testing can confirm that a patient is at risk for a growing number of medical conditions long before symptoms appear. And individuals can get personal genetic tests and results simply by going on the web. Access to genetic information bears potential harms as well as obvious benefits. Contributors to this month's issue examine the many ethical questions—from informing at-risk relatives of a patient’s hereditary disease to counseling a pregnant couple about prenatal testing—that come with access to genetic information.