>>510001100
>The Irish weren't white and neither were the Italians
For many people they still aren't, specially the Italians, whom many would classify as "Mediterraneans" or some other thing instead of "white".
As I said, the concept of "white" varies from culture to culture, according to the local traditions and necessities. 19th century America was predominantly Anglo-Saxon, hence it felt the need to protect its culture and ethnos by racially classifying the Italians and the Irish as non-white. As that culture changed into something different, so did these classifications.
It won't surprise me if in 100 years "white Latinos" like Messi are also considered white in the USA, just like they are in Brazil and Argentina. You even see some Americans now who consider the Jews and the Iranians as "white". I'd say Jews like Ben Stiller and Scarlett Johansson are pretty much considered "white" in the USA already, and have been for some time. Most Americans would consider them "whither" than Bruno Fernandes, if they were to meet them randomly on the streets.
So it all depends on the culture and the definition it chooses, which may be based on genetics, or may be based on something else (predominant appearance, full appearance, historical ties, etc.)