Bin Laden’s second son, Abdul Rahman, was born with a rare and poorly understood birth defect called hydrocephalus, commonly called water on the brain. It results from an excess of cerebrospinal fluid building up inside the neural ventricles, which in turn causes the head to enlarge and the brain to shrink. After birth, the head continues to expand unless the fluid is drained. Abdul Rahman’s condition was so serious that bin Laden himself took the baby to the United Kingdom for treatment—probably the only time that he traveled in the West. When the doctors told him that Abdul Rahman would need a shunt in his brain, bin Laden declined to let them operate. Instead, he returned to the Kingdom and treated the child himself, using honey, a folk remedy for many ailments.