My father always stressed the importance of blood — being worthy of it, showing loyalty to it, protecting what he called the purity of it. He was, as people sometimes say of well-educated racists, not a stupid man. He had a master’s degree in aerospace engineering, and he was valedictorian of his law-school class. But he considered slavery a benevolent institution that should never have been disbanded, and he viewed his and my fair skin as a mark of superiority.

The world being what it was in my post–civil rights era youth, he had retreated to an ardent, evangelical separatism.…