Sometimes it is fairly safe to assume that a patient is more likely to have a familial disorder than a sporadic form of the same disease. A 39-year-old man was brought to the emergency department by ambulance with chest pain and palpitations. He had a history of migraines and dyspepsia. His family history was remarkable for a sister with Wolff-Parkinson-White syndrome, detected at age 18 years during pregnancy, and a brother with Wolff-Parkinson-White syndrome. The patient’s son, born prematurely, was diagnosed with Wolff-Parkinson-White syndrome at 1 month of age, and he underwent ablation therapy when he was 8 years old.