I'll go back and read this whole thread but I just watched an Australian Sci-fi movie called Predestination. A couple of times in the movie someone was playing I'm My Own Grandpa on a juke box and it turns out that it is a core theme of the movie.

I'll have to watch it again to fully understand it all - like I had to watch Inception a couple more times. It was an interesting concept and I think it was worth watching.

Based on a story by Robert Heinlein called All You Zombies, and I'll now try to find it and read it.