A few years before he became the 26th U.S. president (1901–1909), Theodore Roosevelt got word that his oldest son, Theodore Jr., was ill. While his son would recover, the cause of Ted’s illness hit Roosevelt hard. Doctors told him that he was the cause of his son’s illness. Ted was suffering from “nervous exhaustion,” having been pressed unmercifully by Theodore to become the “fighter” hero-type he himself had not been during his own frail childhood. Upon hearing this, the elder Roosevelt made a promise to relent: “Hereafter I shall never press Ted either in body or mind.”

The father was true to…