When Back to the Future came out 25 years ago, I was too young to see it in theaters. But once I reached video-rental age I kept it—along with E.T. and Clue —in heavy rotation. Starring Michael J. Fox as Marty McFly, a 1980s teenager who accidentally travels back to 1955 and must make his way, as the title has it, back to the future, it's a natural kid's choice. Then again, it deals with topics usually left to adults or, more specifically, to Scandinavian adults: having sex with your parents and encouraging your parents to have sex in front of you.
In elementary school, I was only dimly aware of these incestuous themes. If you've graduated from eighth grade, you can't miss them. I rewatched Back to the Future on the occasion of its quarter-century anniversary (it's newly available in Blu-ray), and can attest that incest is absolutely central to the plot. What's genius about Back to the Future, however, is that it still manages to be unfailingly PG. It's a film about having sex with your family that's family-friendly.
To refresh: We first meet Marty, a skateboard-riding, guitar-playing teen, in 1985. His dad, George (Crispin Glover), lets himself get pushed around by his boss, Biff Tannen (Thomas F. Wilson). His mom, Lorraine (Lea Thompson), drinks too much. Depressed by these losers, Marty looks up to Doc Brown (Christopher Lloyd), who's just fashioned a time machine out of a DeLorean DMC-12. Then, following a Libyan terrorist shootout in a mall parking lot, Marty takes off in the DeLorean and ends up in 1955—the year Doc had the Eureka moment that eventually led to the time machine, and the year that Marty's parents fell in love.
Shortly after arriving in the past, Marty encounters his dad peeping at Lorraine from a tree branch. When George tumbles into the street, Marty saves him from an oncoming car and gets knocked unconscious. Big mistake. The driver is Lorraine's father, and the accident is what's supposed to bring George and Lorraine together. In this alternate history, it brings Marty and Lorraine together, instead. Lorraine develops a crush on her son, and now Marty must figure out not only how to get back to 1985 but how to transfer his mother's affections from himself over to his father. Otherwise, he and his siblings will never be born.
This seems icky. So icky that, when writers Bob Gale and Robert Zemeckis pitched the idea for Back to the Future to Disney, the studio purportedly said that a mother falling in love with her son was not appropriate for their brand. Universal green-lighted the project, but Disney's objection was not lost on producer Steven Spielberg, who once told Empire magazine that he "thought the Oedipal aspect was really gross."
Lorraine's infatuation never feels un-Disney, however. Back to the Future presents mother-son attraction not as a perversion, but as one of those things that just happens and kinda makes sense, if you think about it, since in this reality mother and son are the same age. Gale came up with the Back to the Future concept while flipping through his father's high-school yearbook. He thought, "Gee, if I went to high school with my dad, would I have been friends with him?" The Lorraine-Marty situation is not so different. If father and son had been contemporaries, would they have been friends? If mother and son had been contemporaries, would they have dated?
Lorraine, of course, has no idea that Marty is her son—she doesn't want her offspring, really, but a hot, young stranger. Marty realizes that Lorraine's his mother, so there's more room for viewer-horror when he remarks on her attractiveness. ("You're my ma, you're my ma … but you're ho … you're so, uh … thin" he stumbles.) What keeps this moment comic rather than Greek-tragic is that Lorraine is … thin; Marty's merely expressing an uncomfortable fact.