The notorious feud between the Hatfield clan in West Virginia and the McCoy family in Kentucky lasted for over 100 years. Over the past few decades, doctors have tracked a disease in the McCoys that may explain at least some of the violence. Von Hippel-Lindau disease has been diagnosed in many members of the McCoy family over several generations. It causes tumors, especially in the adrenal gland, which can lead to high blood pressure, pounding headaches, and too much adrenaline. Researchers have known about the disease in the McCoys for decades, but did not reveal the patient’s names due to confidentiality and insurance concerns. Link -via Metafilter