I genuinely believe that his parents were so ashamed their little kid was such an asshole since he learned how to talk, they just told him he was italian to deflect responsibility and protect the pride of the polish people.Leave it to a Polack to be so dumb that he thinks he's Italian.
You know family reunions were awkward:
Uncle: "Why does little Philip keep saying he is Italian?"
Dad: "He is an idiot, we have purposely thought him wrong to hide our shame"
Uncle: "Well, can't say I blame you, pass the pierogi"
Phil: "What is that?"
Uncle: "This are, huh, ravioli, yes, ravioli! Its a traditional italian dish Phil!"
Phil: "Wow, it's tangy"