This is actually an important Generation X movie. Generation X starts in 1961 (some say '64), and so the target audience for Back to the Future (BTTF) was Gen-X in 1985. The key thing though is these were the children of the Silent Generation (almost as bad as Boomers). The famous generation gap of the '60s was in the rear-view, which we could argue was really a divide of "people who could not have premarital sex with the pill vs. people who had the pill". These kids watching BTTF were children of Silents or early Boomers, and had just left the '70s behind where their parents engaged in key parties, swinging, skyrocketing divorce, re-entering the dating market and then remarrying. Yes, their folks were mom and dad, but due to the divorce and dating game, how many Gen X children had a twist on their perception of Mom or Dad also pulling in someone for naughty fun? That changes things, and suddenly they are a three dimensional person, not just mom or dad. That suspicion and confirmation that your parents are and have always been horny just like you are is throughout the film and was throughout the audience's shared experience.
"Whoa wait a minute Doc... are you telling me... my parents had key parties... when I was 10???"
Remember, Marty travels back in time by accident and needs to go back home. The parent fix is accidental; the sexual dynamics are not. Marty McFly goes back in time and how does he "meet" his dad? He finds him peeping on women. What is his main interaction with his mom? She is all about getting into his pants, and even was in his pants because she sees him in his underwear when he is knocked out (hence thinking his name "Calvin Klein"). It is an incestuous situation where he has to fend off his mom, but not an Oedipal situation because he is not the one seeking his mom's love. If anything, it is an inversion of Oedipus as Marty must strengthen father George and reject the willing sexual partner Lorraine. This is the entire set up, and yes, Silents were having sex in great numbers.
"Whoa wait a minute Doc... are you telling me... people had pre-marital sex, before '68???"
Drive Ins were popular. The term teenager was invented. All of those '50s teenager songs (and early '60s) involve getting a car to go driving with your sweetheart at night, parking at the drive in or a girl singing about her rebel boyfriend who had a car. Wink wink, nudge nudge we're sexually active in that car. Think about Marty's plans with his girlfriend at the beginning of the film: get sleeping bags, camp out under the stars, wink wink bang it out. Too bad I have to hide it from my parents. Now he goes back in time and sees their hypocrisy, confirming a suspicion. Marty has to coach his dad on being a man to directly get down to loving, not creepy peeping, and he has to tone his mom down so she will properly see the good man George can become to not just have car sex with but love and marry. I can fix this!
"Whoa wait a minute Doc... are you telling me... geek to chic is possible? Wait, hold on, that's a line from Can't Buy Me Love."
The nurture over nature starts immediately with Marty trying to coach up his dad, George, especially with regards to standing up to Biff. See dad, be a man! Each move ends up pulling his mom towards Marty and not George. George just cannot do it. Marty discovers his dad was a sci-fi nerd, and a bit of a creative guy (they share some self doubt). What's dad doing working a ho-hum job being bossed around by Biff in 1985? George cannot do it. He cannot be a man. At the very end, George toughens up and knocks Biff out, winning Lorraine's heart and making Marty's existence and unique soul possible.
"Whoa wait a minute Doc... are you telling me... births + existence aren't accidental like progressives say???"
This coaching is while Marty is holding Lorraine off for over an hour onscreen, acting as the only sexual restraining force on her that viewers see. Not her parents, not her friends, not society around them, just 17 year old Marty. His mom admits to parking before, as well as drinking and smoking. The suppressive '50s culture may not have been as restrictive as portrayed by 2015 cultural gatekeepers. The horror to it is that Marty only restrains her due to the taboo of incest and the need to get his parents together to secure his existence. Exactly what were we liberating women from? No fault divorce, abortion and the pill? Is that all? It is 2015. Do we have zero abortions due to pill use? Do we have zero illegitimate children due to abortion and pill availability? What was it for?
"Whoa wait a minute Doc... are you telling me... my mom was a whore??? This is heavy."
Marty's coaching of them both, but especially George being inspired to man up, changes their lives. Marty comes home to 1985 to discover that George is a published author. Lorraine looks great. His siblings, despite the same genetic source as before, are now portrayed as successful compared to the introduction scene. Marty has the rad '80s truck for his date. Biff is now the apologetic, loser who bows down to George. It's all fixed*. The awesomeness was always there, Marty helped George find it. Nurture wins!
"Whoa wait a minute Doc... are you telling me... women want strong men and not male feminists???"
An interesting thing about his parents' relationship is that now its origin story is better. Forget the fact that they'd realize around age 13 that their son went back in time and interacted with them (BRILLIANT idea for SNL skits: The McFly Family Therapy Sessions!). Lorraine originally fell for George because her father ran him over with his car, and she helped nurse him back to health. She now fell in love with George because he decked a tough bully who was attacking her, knocked over some ginger loser and kissed her on the dance floor. It is not a pity connection but a "macho win her heart" routine. She's not drinking herself silly, looking at life with a schlep her dad ran over and three meh kids. She has successful kids and a successful husband who she can admire that has always been a man for her. All because of Marty's coaching and one specific set up. See kids, the people do not matter, just put them in the right scenario with the right preparation. It's like the American approach to educating disadvantaged kids to compete in the hi-tech economy.
"Whoa wait a minute Doc... are you telling me... we can't 'close the gap' using new teaching techniques???"
It has been thirty years since BTTF came out. How could they set that up today? Would the kid want to fix his parents? Isn't that a common Hollywood cliche: kids hate their parents. When he finds out that his siblings, and he himself, are evaporating into non-existence, would the movie stop as a hipster said "I'll take my chances in the nothingness of Buddha/reincarnation/different form". This was a pop culture movie so there was no all night session between Doc Brown and Marty in 1955 about what if Marty will not be Marty with his parents split, but he would be a different kid or 2 kids. That would be a deleted scene that I'd enjoy. Right now, SNL could have fun with Back to the Future considering the sequel takes place partly in 2015. They haven't.
"Whoa wait a minute Doc... are you telling me... that SNL missed a goldmine for possible sketches???"
Now I've spent too many words on a sci-fi comedic film from the '80s, but here's the quirk. Marty did not go back to fix his parents**, but we all understand it that way. He went back and messed with the timeline of his parents meeting. Just to get them to meet and fall in love again, he creates a new order of events that causes all of the behavioral changes. Nurture wins. We all bought into the subtext that Marty was fixing his parents, saving them from a lower middle class existence in '80s California. They have the same house that now is arranged to display an upper middle class existence, but we the audience do not care. He fixed his parents. Nurture overcomes nature. Those Generation X viewers, leaving the theaters in 1985, had to be thinking, "God, if only I could go back and fix my totally lame parents".
*What did not need fixing? The script. Brilliant work with memorable lines and a well paced story with three plotlines: 1. Marty sets up and fixes his parents, 2. Marty + Doc make the flux capacitor work, 3. Marty spends time with, appreciates and saves his friend Doc who he knows he will never see alive again.
**Shhhh, Back to the Future 2 is every parent's dream: fix your kids.
Let's end this with a great indie song inspired by the film.