a biological explanation for the Hatfields and the McCoys?

The most famous feud in American history might have been exacerbated by a rare condition.

Von Hippel-Lindau disease, which afflicts many family members, can cause tumors in the eyes, ears, pancreas, kidney, brain and spine. Roughly three-fourths of the affected McCoys have pheochromocytomas — tumors of the adrenal gland.

The bubbly-looking orange adrenal glands sit atop each kidney and make adrenaline and substances called catecholamines. Too much can cause high blood pressure, pounding headaches, heart palpitations, facial flushing, nausea and vomiting. There is no cure for the disease, but removing the tumors before they turn cancerous can improve survival.

Affected family members have long been known to be combative, even with their kin. Reynolds recalled her grandfather, "Smallwood" McCoy.

"When he would come to visit, everyone would run and hide. They acted like they were scared to death of him. He had a really bad temper," she said.

Her adopted daughter, another McCoy descendant, 11-year-old Winnter Reynolds, recently had an adrenal tumor removed at Vanderbilt Children's Hospital. Her teachers thought the girl had attention-deficit (hyperactivity) disorder. Now, Winnter says, "my parents are thinking it may be the tumor" that caused the behavior. "I've been feeling great since they took it out."

The wider implications, adding to a growing body of research linking particular ailments and abnormal behavior, are equally interesting. Perhaps there's some truth to the 19th century view of a "moral disease."