Do Jokes and Babies Come From the Same Place?

Almost twenty years ago, I went through a phase where I memorized a bunch of jokes . . . and then I got to wondering where the jokes originated from-- it's not like when someone tells a joke they also mention the author (this is "Three Penguins Walk into a Bar" by Joseph Shmoe) and so just before I got married-- over fifteen years ago-- I created a few of my own jokes, and told them to as many people as would listen, with the hope that they would enter the ether and propagate; most of the jokes were quite bad and incredibly vulgar and I won't even summarize them on this blog, but one of the bunch was actually decent . . . and last Thursday night at the pub my friend Alec started reciting a joke that he "heard from a guy in the city" and I immediately recognized it as one my own and I was enormously excited . . . but there were a few differences between the joke I created and the one Alec told, and when I looked on internet, I found this version of the joke surfacing around 2005 under the very specific category of "motorcycle humor," and now I am wondering if I heard this version of the joke first and repurposed it so it wouldn't be so specific to motorcycle enthusiasts, or if my version got around and some motorcycle enthusiast retooled it to fit his audience . . . I suppose I'll never know for sure, but it was a fun moment (and also, I should point out that my friend Whitney claims he invented Movie Game #2 and I've got no reason to doubt this, so let's give him a big round of applause for that stroke of genius).