This article presents an approach to "thinking genetically" in primary care. Busy practitioners often lack the time to consider thoroughly whether their patients have an underlying genetic diagnosis. To assist the primary care clinician, a working group of the Genetics in Primary Care Faculty Development Initiative developed a simple mnemonic, Family GENES, that alerts the clinician to consider genetic causes in the differential diagnosis. In addition to family history, the red flags include Groups of anomalies, Early or Extreme presentations of common diseases, Neurodevelopmental or Neurodegenerative conditions, Exceptional or unusual pathology, and Surprising laboratory values. This article discusses the components of the mnemonic, provides examples, and gives guidelines to appropriate actions once the possibility of a genetic diagnosis has been raised.