According to the standards set by Jews themselves (which differ slightly according to denomination), a Jew is usually someone born of a Jewish mother (but in very liberal cases, a paternal line is sometimes acknowledged today). "Jewish" means someone who formally belongs to a Jewish denomination (i.e., Orthodox, Conservative, Reform, Recostruction, Humanistic) or community (Sephardi, Misrahi. Beta-Israel). Belief or faith in any tenet is often not a requisite in Judaism.
Are any of the members of the Governing Body therefore considered Jewish? Not likely in any sense of the word, nor do I think they consider themselves that.
One of the factors that gives this away is the Jewish value of education that is built into the culture. From antiquity, Jews have been known to be great learners, educators, developers of great schools, yeshivas and universities, and have striven to send their children there. The idea that there are no scholars on the GB who have gone to a yeshiva or seminary is a clear indication that none of them are Jewish.
Another thing is that JWs use the Divine Name, using the term "Jehovah" (which has no meaning to Jews because it was a mistaken invention by Christians), and call it the Tetragrammaton. Jews don't use the Name, prefer "HaShem" or "Eternal" or "Adonai" instead, and say Shem HaMamephorash (Hebrew) instead of Tetragrammaton (Greek) for the letters of the Name of God. So the GB obviously never stepped foot into Hebrew School, which they would have done since they were toddlers if they had been brought up Jewish.
They are not really obsessed with "Jewish principles." All their obsession with the Old Testament comes from the Adventists who became the Seventh-day Adventists. The SDA believes that the Law still applies to Christians and have odd ideas that the Hebrew texts apply to the Church in weird allegorical ways. The Bible Students were once connected to the Adventists, and took all the foundational beliefs--especially the Last Days--from them. So this is where the focus on the Hebrew Scriptures comes from.
