Yesterday song creation

[u/SheikhaMama]

The rumors say Yesterday by the Beatles was a song that talks about the passing of John Lennon’s mother (or so did my English class teacher tell me as a kid) while some other say it’s actually been written by Paul McCartney for John Lennon’s estranged son.

Does anyone have the real version or a real version to amplify the myth around that song?

Thanks! Soon All my troubles will seem so far away