“Telling a teenager the facts of life is like giving a fish a bath.” — Arnold H. Glasow

In Marielle Heller’s directing and screenwriting debut, taken from Phoebe Gloeckner’s novel, we meet Minnie (Bel Powley from Britain). Minnie, kind of a precursor of Lena Dunham’s “Hannah,” is a child of her times. Sadly for Minnie, her times happen to be that chaotic, smoky cesspool that so many kids drowned in from the late ’60s to the ’70s, as they took the streets.

This is not actually the case for Minnie, a horny, very bright, gifted artist of graphic diaries (and a pretty good film actor) who is not on the streets. This is not a street movie. It’s scarier. Some homes are more dangerous to coming of agers than the streets.

This is where we find Minnie. Minnie has a mother, Charlotte (Kristen Wiig.) Unfortunately for Minnie, Charlotte is a fragmented, emotional cripple who thinks herself a feminist, and has just lost her job in a library. Charlotte has never met a drug she didn’t like.

Charlotte has a boyfriend Monroe, (Alexander Skarsgard) probably her sixth, a lout who has dreams, all the result of the multiple drugs and booze he shares with Charlotte and their coterie of druggy friends. He dreams of creating a mail order business of vitamins. Yes, he does.

The 34-year-old Monroe, who is ever present, has picked up the scent of 15-year-old Minnie, and Minnie sees him as her guide to the sexual garden of delights. What could possibly go wrong?

Minnie’s real father may have been anyone, a low end rock guitarist or a druggist with an open heart, knowing the promiscuous gifts of Charlotte.

There is Pascal, (Christopher Meloni, sans badge) a decent, well-educated professor, who was the girls’ first stepfather. Pascal lives elsewhere, but makes time once in a while to sit down in a cafe with Minnie and her baby sister, Gretel (an enchanting Abby Wait) to correct their grammar and try to discuss ways to hold all the loose ends of their lives together.

Pascal pays for their better-than-usual school, and occasionally drops in a thousand-dollar check, so that his kids don’t starve. Of course Charlotte uses the cash to throw private drug soirees.

Meanwhile, Minnie dreams of sexual liberation fueled naturally by the constant flow of promiscuous wind in her life. This will result in 102 minutes of cute, animated cartoons and illicit grappling.

The cast: Kristen Wiig, formerly of “SNL,” doesn’t seem to have grown much as an actor since “Bridesmaids.”

Skarsgard (“Generation Kill,” and ” Battleship”) is a graduate of the Channing Tatum school of acting. The key here is that except for the little girls, we don’t care much about anyone, but there may be a future for Minnie, a young British actor, very bright, gifted future artist.

At the end, after Monroe confesses his illegal tryst with Minnie, Charlotte, obviously still tripping, suggests a marriage between Monroe and Minnie, keeping him out of jail and Minnie home. Happily that doesn’t happen. The ’80s lie ahead. Good luck to them all.

J.P. Devine is a former stage and screen actor.