More family stuff

I have two brothers: one from the Ohio bunch, and another from California. Bro I is a religious fanatic and so is his wife. Bro II is a proud atheist with a wife who is not very religious but thinks Chanukah is fun.

Brother I and wife have managed to produce three atheists. His oldest son is an Arabist. The son of Brother II has just come back from Israel and is devoting his life to the Zionist cause, and has a tattoo that says "Forever" or "never again" or something of that nature on his arm. The daughter of II spent the summer in Israel. Since she's only 15, her religious and ethnic sympathies are not yet known.

Where did these two families go wrong?