As deranged manifestos go, the final YouTube video made by suspected Isla Vista, Calif., mass murderer Elliot Rodger was remarkably well-made. Filmed by Rodger in his black BMW, with palm trees in the background and his face bathed in magic-hour key light, the six-minute diatribe — during which he vows revenge on all the women who rejected him and men who were enjoying fun and sex while he was “rotting in loneliness” — might easily have been mistaken for a scene from one of the movies Rodger’s father, Peter Rodger, worked on as a director and cinematographer.

Indeed, as important as it is to understand Rodger’s actions within the context of the mental illness he clearly suffered, it’s just as clear that his delusions were inflated, if not created, by the entertainment industry he grew up in. With his florid rhetoric of self-pity, aggression and awkwardly forced “evil laugh,” Rodger resembled a noxious cross between Christian Bale’s slick sociopath in “American Psycho,” the thwarted womanizer in James Toback’s “The Pick-Up Artist” and every Bond villain in the canon.

As Rodger bemoaned his life of “loneliness, rejection and unfulfilled desire” and arrogantly announced that he would now prove his own status as “the true alpha male,” he unwittingly expressed the toxic double helix of insecurity and entitlement that comprises Hollywood’s DNA. For generations, mass entertainment has been overwhelmingly controlled by white men, whose escapist fantasies so often revolve around vigilantism and sexual wish-fulfillment (often, if not always, featuring a steady through-line of casual misogyny). Rodger’s rampage may be a function of his own profound distress, but it also shows how a sexist movie monoculture can be toxic for women and men alike.

How many students watch outsized frat-boy fantasies like “Neighbors” and feel, as Rodger did, unjustly shut out of college life that should be full of “sex and fun and pleasure”? How many men, raised on a steady diet of Judd Apatow comedies in which the shlubby arrested adolescent always gets the girl, find that those happy endings constantly elude them and conclude, “It’s not fair”?

Movies may not reflect reality, but they powerfully condition what we desire, expect and feel we deserve from it. The myths that movies have been selling us become even more palpable at a time when spectators become their own auteurs and stars on YouTube, Instagram and Vine. If our cinematic grammar is one of violence, sexual conquest and macho swagger — thanks to male studio executives who green-light projects according to their own pathetic predilections — no one should be surprised when those impulses take luridly literal form in the culture at large.

Part of what makes cinema so potent is the way even its most outlandish characters and narratives burrow into and fuse with our own stories and identities. When the dominant medium of our age — both as art form and industrial practice — is in the hands of one gender, what may start out as harmless escapist fantasies can, through repetition and amplification, become distortions and dangerous lies.

Every year, San Diego State University researcher Martha Lauzen releases a “Celluloid Ceiling” report in which she delivers distressing statistics regarding the state of women in Hollywood. This year, she found that women made up just 16 percent of directors, writers, producers, cinematographers and editors working on the top 250 movies of 2013; similarly, women accounted for just 15 percent of protagonists in those films.

Even if 51 percent of our movies were made by women, Elliot Rodger still would have been seriously ill. But it’s worth examining who gets to be represented on screen, and how. It makes sense to ask, as cartoonist Alison Bechdel does in her eponymous Bechdel Test, whether a movie features (1) at least two named female characters who (2) talk to each other about (3) something besides a man. And it bears taking a hard look at whether we’re doing more subtle damage to our psyches and society by so drastically limiting our collective imagination. As Rodger himself made so grievously clear, we’re only as strong as the stories we tell ourselves.