Cultural Jewishness

This is a bit of a throw back to my last update but I think it's certainly post-worthy none-the-less.

A new book is coming out, The Finkler Question by Howard Jacobson, and it holds the question of Jewishness (in this case, 'cultural Jewishness') front and center.

"What does it mean to be Jewish? To some it means sitting down at Katz's delicatessen with a pastrami sandwich. To others, it's setting up a hilltop outpost in the West Bank and waiting for the messiah. That essential uncertainty, pondered by everyone from rabbis and philosophers to Shakespeare and Sammy Davis Jr., is what Howard Jacobson tackles head on in The Finkler Question.
...
The story revolves around Julian Treslove, a melancholy, lackluster London liberal. After Treslove is mugged one night, he believes, with increasing certainty, that his attacker called him a Jew. Though his best friends are Jewish, Treslove is not. Or at least he's fairly certain he isn't. But as a result of the incident, he becomes increasingly obsessed with the question of Jewishness.
Treslove doesn't approach his journey into Judaism from a religious standpoint. He takes no steps to learn Hebrew or convert. Instead, his obsession is cultural. He wishes to understand the mannerisms of Jewish life; the hidden code of Jewish sarcasm and the subtleties of Jewish body language.
As Treslove yearns to pass as a Jew, many of his Jewish contemporaries in the book do their best to pass as gentiles, including one pitiful character who spends his waking hours trying to reverse his circumcision, chronicling his efforts on a blog, photos and all."
'Finkler' Questions the Meaning of Jewishness - David Sax [All Things Considered]

I quote this article because the commentary on The Finkler Question explores something we see Art Spiegelman exploring in Maus I and II- what exactly makes someone Jewish and to "what extent" are they Jewish (further still, what specifically are the qualifiers and how important is each box that must be checked)?  In the case of Maus, who gets to be painted as a mouse and who just gets a mouse mask; is it fluid?

From my limited understanding there are several different interpretations of Jewish identity.  Honestly?  I think we see this is any minority or even subculture: larger identity in dispute, "truer than you" language, sometimes more laid back interpretations and a general acceptance of splinter/sub-identities.