Their strength lay in the stories, passed from generation to generation. And so when descendants of Thomas Woodson rolled up their sleeves to give blood for DNA testing, they saw it as a chance to affirm their faith--that Thomas was, in fact, a child of Thomas Jefferson and his slave Sally Hemings. "We knew it like religion," says Robert Golden, Thomas' great-great-great- grandson. The results, however, came as a shock: Jefferson was not Thomas Woodson's father.
Similar DNA tests, as the world now knows, established that the youngest of Hemings' sons, Eston, was Jefferson's child. Yet amid the intense debate about...