What does it mean to give a genealogy of morality?

Nietzsche wrote On the Genealogy of Morals about the origins of the moral principles that govern Christian society. He was interested in the history of the development of modern morality, and he speaks in the Preface of his book about his early interest in "what origin our terms good and evil actually have." He faulted English psychologists of his day for what he called their lack of the "historical spirit," and he tried to trace the ways in which our current morality developed.

Therefore, to give a genealogy of morality is to trace the genesis, or origins, of our ideas about what is right and what is wrong. To provide the history of morality is to oppose the traditional Christian idea that morality comes from God. For example, in his first essay, Nietzsche argues that the concept of "good" came to be associated with nobility, while what was not good was associated with those who the nobility considered inferior. Therefore, his genealogy of morality was rooted in psychology and sociology rather than in religion.