Every year in the U.S., many people celebrate the Feast of the Seven Fishes on Christmas Eve. Although it is unclear when the dinner became so popular, this celebration is considered one of the most Italian traditions. Typically, the family gathers round a feast of seven different seafood dishes or one or two different types of fish prepared in seven different ways.

Despite its popularity among Americans, many Italians do not even know about the tradition — or its origin. Surprised? The answer can be found in the bio-diversity of Italy: the country boasts so many differences between the north and south.