There’s a rich Hollywood tradition of glib treatment of the mentally ill — movies with the medically disastrous “all they really need is love” message.

The simplistic melodrama “My Brother, My Sister (Mio fratello mia sorella)” flirts with giving us an Italian twist on that Hollywood “cure.” But it doesn’t wholly embrace that idea even at its soapiest. What we see here is a sometimes glum portrait of a family drowning in the illness of one member, unable to see that until the irresponsible prodigal brother (uncle) returns.

Haggard Tesla (Claudia Pandolfini) is presides over a properly weepy Roman Catholic funeral for her father, an astrophysicist whose life merits many a tearful testimonial.

Until, that is, a RayBanned beach bum strolls in and steps to the pulpit. Brother Nik — their dad named his kids “Nikola” and “Tesla” — has a different take, one a little off script. Tesla’s fury at the sibling (Alessandro Preziosi) she hasn’t seen in many years has just begun.

Their dad left them the family apartment — together– which the movie tries to convince us is only three rooms. Somehow, they’ll have to reconnect and work things out, and it might just take them a year.

It’s just that Tesla never told Nik that her son, Sebastiano (Francesco Cavallo) is schizophrenic, filled with tics and chatter with this Martian, “Kelvin,” inside his head. He’s a gifted cellist, and not the only musician in the family. But the apartment is papered over with Post It notes, reminding him of this or that, and everybody else of the medications, routines and bubble they’ve turned all their lives into to help him cope.

Tesla’s despair is that “surfer philosopher” (in Italian with English subtitles, or dubbed) is a disruption that their world cannot withstand.

Her college age daughter Carolina (Ludovica Martino), whose rebellion has taken the form of addressing her mother by her first name, uses her inheritance — grandpa’s old RV — to move out. She’s given up enough of her life to her brother’s care.

And Sebastiano’s piano accompanist, Emma (Stella Egitto), keeping to a strict routine to “help” Sebastiano, frets over Nik’s interference even as she despairs of ever being able to perform with “Seba” publicly.

Nik, given to random moments of nudity and naked romps with young women he’s picked up while kite-surfing on the beach, is a bull in their china shop of rigid routine, enforced quiet and lives totally built around the sick person in their midst.

Old wounds will be opened, a sibling rivalry half-renewed and ugly secrets exposed as Nik “interferes” with one and all, and that routine is shaken up.

Pandolfini (of “Cuanda da Note, When the Night”) and Preziosi (“None Like Us”) have an apt brittle chemistry, and the supporting players have just enough good scenes to lay out each one’s agenda.

Cavallo’s catalog of nervous twitches and banter with the voice inside his is reasonably convincing, in a “movie version of schizophrenia” way.

The “secrets” are a mix of “Wow, didn’t see that coming” and “Really, who couldn’t see THAT coming?”

There are several points where writer-director Roberto Capucci — the soccer road-trip comedy “Ovunque tu sarai” was his — could have turned this into something lighter, if less psychologically defensible.

But even Sebastiano stumbling into Nik’s nubile, naked new girlfriend in the bathroom never quite plays as a laugh.

The film takes on the timid/don’t-make-noise tone of the family, living under the cloud of the gifted cellist’s illness. Nik has old issues to resolve, Tesla has to take stock and Carolina asserts herself as a fashionista once she’s out from under the family’s roof. But Sebastiano’s part of the story smothers the life out of the rest of it.

That makes for a drab mental-illness-in-the-family Italian melodrama, one without much in the ways of upbeat highs or soul-crushing lows.

Rating: TV-MA, nudity, sexuality, smoking, drinking

Cast: Claudia Pandolfini, Alessandro Preziosi, Ludovica Martino, Stella Egitto, Francesco Cavallo and Caterina Murino

Credits: Scripted and directed by Roberto Capucci. A Netflix release.

Running time: 1:53