I've never been comfortable with the term "race" when applied to people, as people are all part of the "human race". But, according to thefreedictionary.com, the word "race" is defined as:
A group of people identified as distinct from other groups because of supposed physical or genetic traits shared by the group. Most biologists and anthropologists do not recognize race as a biologically valid classification, in part because there is more genetic variation within groups than between them.
A group of people united or classified together on the basis of common history, nationality, or geographic distribution: the Celtic race.
A genealogical line; a lineage.
Humans considered as a group.
a. A usually geographically isolated population of organisms that differs from other populations of the same species in certain heritable traits: an island race of birds.
b. A breed or strain, as of domestic animals.
A distinguishing or characteristic quality, such as the flavor of a wine.
Based on any of those definitions, are the Jewish people a race? (When I say "Jewish people", I am referring to people who are Jewish according to how the members of this specific website, mi yodeya StackExchange define Judaism; please see "Am I Jewish?" and How does someone not know they're Jewish? for details.)
What about the subset of of the Jewish people (as defined in the previous paragraph) who, to the best of their knowledge, never had any family members who converted to Judaism?