Mathematically speaking, having a father who is half Italian would make you a quarter, or 25%, Italian. This is because, in this hypothetical equation, you would have received 50% of your genetic information from him, (with the other 50% coming from your mother). If your father were 100% Italian, this would mean that you would be 50% Italian. However, as your father is half-Italian himself, the genetic information passed on to you by your father would theoretically need to be divided into a further two halves, resulting in a total of 25% Italian.
These days, with the melting pot of culture and ethnicity that our world has become, it is very common for people to have a rich and diverse background or heritage. Travel, trade, colonization, religious persecution, famine and even slavery are only some of the historically relevant factors that have resulted in population growth and cultural change over the centuries. For this reason, it is almost impossible to trace back more than a few decades in a person's family tree without coming across some form of 'foreign link'.
Italian immigration, especially to the United States, peaked between 1876 - 1924, during which time almost 4.5 million Italians left their homeland in search of better conditions in the US. And whilst 30% of these immigrants eventually returned to Italy, many more made America their permanent home and became responsible for a considerable amount of the Italian heritage that modern Americans share to this day.
