Many years after making his way to America from Odessa in Soviet Ukraine, Emil Draitser made a startling discovery: every time he uttered the word «Jewish»—even in casual conversation—he lowered his voice. This behavior was a natural by-product, he realized, of growing up in the anti-Semitic, post-Holocaust Soviet Union, when «Shush!» was the most frequent word he heard: «Don't use your Jewish name in public. Don't speak a word of Yiddish. And don't cry over your murdered...