In the NYT Magazine, Gershom Gorenberg has an article entitled "How Do You Prove You're a Jew" that echoes what I've been saying about the definition of what a racial group is for years:

Zvi Zohar, a professor of law and Jewish studies at Bar-Ilan University, told me that in Judaism’s classical view of itself, Jews are best understood as a ”large extended family” that accepted a covenant with God. Those who didn’t practice the faith remained part of the family, even if traditionally they were regarded as black sheep. Converts were adopted members of the clan.