This commentary contrasts two recent scholarly works on the possibility of a biological basis for “Jewishness.” Harry Ostrer's Legacy: A Genetic History of the Jewish People claims a strong shared genetic component of Jewish ancestry tracing to the Levant, extending so far as to suggest a biological basis for Jewishness. Nadia Abu El-Haj's The Genealogical Science: The Search for Jewish Origins and the Politics of Epistemology adopts a skeptical perspective on contemporary genetics and claims that genetic studies of the Y chromosome and mitochondrial DNA cannot be viewed as supporting a common Jewish ancestry. The disagreement is consequential, and the arguments can be understood in terms of differences in the audiences, styles of reasoning, and social and political perspectives for the two works. A synthesis is proposed for helping to articulate a space between the two opposing views.