The question of ancestry has been of human concern in virtually all cultures and over all times of which we have any knowledge. Whether it be a story about the origin of a particular tribe or nation and its subsequent mixture with other groups, or curiosity about a family history, there is always the implication that we understand ourselves better if we know our ancestors and that we, within ourselves, reflect properties that have come to us by an unbroken line from past generations. As treasurer of the Marlboro Historical Society in Vermont, I am the recipient of requests for printed copies of the Reverend Ephraim Newton’s mid-eighteenth-century history of our town, 70 percent of whose pages consist of “Genealogical and Biographical Notes” and a “Catalog of Literary Men.” Over and over our correspondents write of the “pride” they have in descending from these early settlers.

Surely pride or shame are appropriate sentiments for actions for which we ourselves are in some way responsible. Why, then, do we feel pride (or shame) for the actions of others over whom we can have had no influence? Do we, in this way, achieve a false modesty or relieve ourselves of the burdens of our own behavior? As a descendant of late-nineteenth-century Eastern European immigrants I cannot depend on Reverend Newton’s pages to explain my frequent contributions to The New York Review, but neither have the extensive “begats” in Genesis 10 or Matthew 1 been more enlightening.

My own skepticism notwithstanding, the belief is widespread that knowledge about the personal characteristics of ancestors who have never directly entered into our lives is relevant to our own formation. Moreover, that relevance is seen not simply as arising from our conscious knowledge about those ancestors, but from a deeper source, our genetical inheritance, which also would operate to form us in part, irrespective of our consciousness of the past. That belief is summed up in the title of Harry Ostrer’s book, Legacy: A Genetic History of the Jewish People. It is also implied in the title of a book by Raphael Falk, Zionism and the Biology of the Jews, whose English translation from the Hebrew original has yet to appear.1 While the term “race” is not used explicitly in these titles, in large part because the term is so loaded, there is considerable discussion of the Jews as a race or, using a less charged word, as a “people.”

“Race” is a term of uncertain etymology and many meanings. It may refer to a whole species (the “human race”), a collection of loosely related individuals with a common appearance (the “white race”), a nation (the “race of Englishmen”), or a single family (“he was the last of his race”). Compounding the ambiguity is the…