I’m always interested to learn about influences on culture and traditions that are otherwise taken for granted, or are considered “natural”. So I’m pleased to find out via Wikipedia about “The Pizza Effect” as one perspecive on such a phenomena:

“(…) phenomenon of elements of a nation or people’s culture being transformed or at least more fully embraced elsewhere, then re-imported back to their culture of origin, or the way in which a community’s self-understanding is influenced by (or imposed by, or imported from) foreign sources. It is named after the idea that modern pizza toppings were developed among Italian immigrants in the United States (rather than in native Italy, where in its simpler form it was originally looked down upon), and was later exported back to Italy to be interpreted as a delicacy in Italian cuisine.”