The term "butterfly effect" has been around for a long time, but for better or worse it was popularized by the 2004 Ashton Kutcher movie. For anyone unfamiliar, the butterfly effect describes the phenomenon in which one random event or choice impacts something seemingly unrelated (e.g., the old myth about how a butterfly flapping its wings can cause a hurricane in another part of the world).
The butterfly effect is often used in movies, shows, and books to explain time travel and how doing something like stepping on a butterfly in the past can domino into the apocalypse in the future. As evidenced by Reddit, there doesn't need to be a sci-fi hook for butterfly effect stories to happen, you just need to trace a major event back far enough.
From Redditor /u/busytoothbrush:
My mother wore heels to work and slipped on the carpeted steps, resulting in a broken high heel and a broken leg. While she was home recovering, she somehow developed allergies that led to her needing an inhaler*.
The inhaler* interfered with her birth control and now I have a brother 13 years younger than me.
*Edit: mother confirmed that it was the penicillin that she was prescribed.
From Redditor /u/avocadopixels:
Grew up speaking Spanish so in high school my mom made me sign up for French. I didn’t really care, but figured whatever at least it’s something new. I was a good kid, bit of a cut up with absolutely 0 direction.
In that class I met a girl and we sort of became friends. She got sick that year, cancer. It was horrible. Visited her in the hospital, got close to her family (still am), she passed the following year.
French it turns out was her favorite subject and her dream had been to study abroad. Her parents asked if we (her friends from that class) could do that for her.
The years went on, I worked every summer try to save up to study abroad. I noticed the others who had made the promise weren’t making moves towards it, so I worked even harder. Finally went for a semester my 3rd year.
Tbf I always enjoyed French, but it wasn’t a passion. Except that semester something kind of shifted. Came home, finished undergrad, then got into a masters in French. The whole time my friend’s mom is excited, feeling like my friend is somehow vicariously living through me.
I graduated from my masters and then moved back to France. Been here 3 years now, and May 1st was the 11th anniversary of my friend’s [passing.]
As I type it out it’s not so outwardly obvious, but the entire time it’s been so clear for me that she’s been with me on this journey.
From Redditor /u/shipscrubber:
High school, I didnt get into the AP history class wanted. Changed up my schedule, including a different gym class, without everyone I knew. I was heartbroken. I really wanted to teach, and without an AP class senior year, I was screwed.
Made a new friend in gym class, who was wearing a volunteer firefighter shirt. He had just joined. Seemed interesting, and he invited me to check it out.
They paid for me to get my EMT. Fell in love with healthcare.
Fast forward quite a while, and I'm an ER Nurse and 'precept' students and new nurses, teaching them how to survive in the ER. I also do public outreach and injury prevention. And I love it. Glad I missed out on my class.
From Redditor /u/plateishot:
I was going out to grab pizza and a case of beer for me and my roommate but he texted me he had a stomach thing so I walked to a restaurant and ordered dinner at the bar and met a girl there and now we are married and have two kids because my roommate had diarrhea.