Seems to be the stock answer but it was the Godfather for me too..
When i was about 10 i noticed it was on & asked my old man if i could watch it. He said no cos it was too violent.
How is it violent? i asked with youthful curiosity! What's it about? i also asked...
I swear my Father looked over his shoulder (we were in our lounge at the time) & whispered "The Mafia!"
Whats the Mafia? i whispered back to him.
A secret society he whispered back.
The intrigue was too much for me to bear. I managed to persuade him to let me watch it & needless to say i was hooked.
Thanks Pops