What is an "original recipe"?

Ok, the title might be a bit strange, but when thinking about this you might realize, that this is really a hard issue.

Ok, short prehistory: Today I was eating a Caesar's Salad in an American Diner around the corner. I ate this kind of salad a long time ago and the two where quite different. Searching wikipedia.org and the net I found some recipes and discussions about which one is the "real" one.
The same thing at cocktails: What is a genuine Mojito, or genuine Caipirinha? Mojito: spearmint or peppermint or just mint? White sugar or brown sugar? This brand of rum or the other one? How many mint leaves? Or the whole mint with leaves and peduncle? Crushed ice or ice cubes? There are thousands recipes and thousands of people claim that their recipe is "the right one"!
Or Spaghetti Bolognese: When is a sauce with minced meat allowed to be called a "sauce bolognese"?

And after all these questions: Is there, or is ther not something like an "original recipe" at all?