NEW YORK (CNS) — A coming-of-age comedy focused on a precocious 16-year-old with a generally upbeat personality ought to have considerable appeal.

But, when set in tension with the seaminess of some of the mistakes to which the protagonist of "How to Build a Girl" (IFC) falls prey on her path to maturity, the film's initial attractiveness is irredeemably marred.

Beanie Feldstein plays smart but socially awkward Johanna Morrigan. Growing up in straitened circumstances in Northern England, Johanna gets little guidance from her parents. Dad Pat (Paddy Considine) still yearns to be a star drummer, as he did in youth, while mom Angie (Sarah Solemani) is suffering from postpartum depression after delivering twins.

Johanna, as a result, relies for emotional support on her gay brother, Krissi (Laurie Kynaston), as she yearns to be perceived as cool. She also draws sustenance from the gallery of historical and fictional figures with which she has decorated one wall of her bedroom; they come to life in her imagination to offer her advice and encouragement.

Johanna gets a seemingly unlikely opportunity to rise above the routine humiliations of life at school when she's hired as a freelance critic by a pop music magazine. But the poisonous spirit of the staff — with one of whom, Tony (Frank Dillane), she starts an affair — turns her toxic. Writing under the penname Dolly Wilde, she wittily savages one act after another.

Though it brings her a certain version of success, Johanna's snarky new persona threatens her friendship with John Kite (Alfie Allen), a sensitive older singer she would like to make her boyfriend. Now the breadwinner in her family, she also becomes overbearing in her behavior toward them, including Krissi.

Based on Caitlin Moran semi-autobiographical 2014 novel, director Coky Giedroyc's cautionary tale is rife with the vulgarity it portrays as characteristic of its working-class milieu. More problematically, it depicts both too explicitly and too flippantly the promiscuity phase through which Johanna passes.

Though implicitly presented as merely a detour on her way to more substantial relationships, and as part and parcel of Johanna's numerous excesses, such a degree of sexual indulgence on the part of an underage young woman ought to evoke a more serious, less breezy tone.

Moreover, while John is steadfastly responsible in refusing to allow his bond with Johanna to become erotic, at least for now, this aspect of her story remains uncomfortable for the viewer. All the more so since one scene finds Krissi interrupting Johanna as she pleasures herself while fantasizing about John.

Feldstein conveys both Johanna's sparkling enthusiasm and Dolly's steamroller rampaging with aplomb. But misguided morals blight both the pleasure to be derived from "How to Build a Girl" and any lessons that might be drawn from it, especially by young movie fans.

The film contains a frivolous view of human sexuality, strong sexual content — including graphic casual activity, masturbation and rear nudity — at least one mild oath, numerous rough and about a dozen crude or crass terms as well as an obscene gesture. The Catholic News Service classification is O — morally offensive. The Motion Picture Association rating is R — restricted. Under 17 requires accompanying parent or adult guardian.