Gene Siskel, left, and Roger Ebert, photographed in Los Angeles in 1986, had a contentious relationship that made their TV shows about movie criticism major hits, as chronicled in Matt Singer’s new book, “Opposable Thumbs.” On the Shelf Opposable Thumbs: How Siskel & Ebert Changed Movies Forever By Matt Singer Putnam: 352 pages, $29 If you buy books linked on …
