Some people say it is a myth, but most people who have friends from different countries in Europe would agree there is at least some truth to the idea there is a cultural difference between places like the UK, Germany and Sweden and places like southern Italy, Spain and Greece. This particularly manifests itself in things like punctuality, attitudes to following rules, open emotional warmth in conversation etc.
So what was the historical cause of this difference? When did it first emerge?
Robert Putnam's Making Democracy is a comparative study of Italy's Northern and Southern regions. He argues that social capital developed in the North due to the relative freedom of people to engage in things like commerce and civic life, while in the South monarchs tried to suppress any such civic life. This led to higher levels of interpersonal trust and civic commitment in the North than in the South.
He got to test his theory when Italy devolved power to its regional governments, which had been created with more or less identical institutions. He tracked various outcome indicators like institutional effectiveness to show the North outperformed the South. Apparently, if you want to know politics (or economic efficiency), long-term historical-cultural differences matter.