Sibling alienation looms large in the screenplays of Sandro Petraglia and Stefano Rulli. Indeed, the cheeky title of their latest collaboration...

Sibling alienation looms large in the screenplays of Sandro Petraglia and Stefano Rulli. Indeed, the cheeky title of their latest collaboration, “My Brother Is an Only Child,” could just as easily have been used for their previous film, “The Best of Youth.”

The story line once more concerns two Italian brothers who become opposites over the course of several years. Still, for all the teasing and taunts that dominate their time together, their bond is essential. It provides the movie with an emotional core that gradually becomes irresistible.

Accio (Vittorio Emanuele Propizio) is a scrawny, brainy 13-year-old who fancies himself a Mussolini-style fascist. His older brother, a born leader named Manrico (Riccardo Scamarcio), is a handsome Marxist who only appears to be the more stable of the pair.

When Manrico’s girlfriend, Francesca (Diane Fleri), gets pregnant, she flirts with the grown-up Accio (Elio Germano), partly because Manrico shows little interest in having a child, but it’s clear she’s committed to no one else.

The movie begins in 1962 near Rome, where Manrico stirs up factory workers and Accio fails to suppress his hormones at a seminary. As the 1970s approach and Manrico begins to act out his beliefs, their seemingly aimless lives establish a more threatening pattern. But there’s room for some frivolity, especially during the performance of a wonderfully ridiculous socialist rewrite of Beethoven’s “Ode to Joy.”

The director, Daniele Luchetti, who also worked on the script, doesn’t try for the six-hour-long heft of “The Best of Youth” (which was originally released as a miniseries in Italy). He’s more interested in telling a slighter story that has its own distinctive dreaminess.

That it clicks is largely due to the daredevil chemistry of the actors playing the brothers, who can be a handful whenever they’re together. Propizio and Germano are especially fearless in suggesting Accio’s callowness, while Scamarcio meticulously hints at Manrico’s scarier nature.

Luchetti makes frequent visual references to the experimental nature of 1960s Italian movies dominated by youth and politics (“Before the Revolution,” “China Is Near”); he can’t resist their go-for-broke qualities. The movie builds to a showy final handheld shot that is likely to strike you as either insipid or inspired.

John Hartl: johnhartl@yahoo.com