World Events in Middlesex!

Why does Cal reference historical events, such as the Turkish invasion, Easter, and Japanese surrender and relate them to his family's history?

By connecting his family's story to weighty historical events, he makes it more memorable. We remember that he was born on Easter; if he had been born on another random day, we wouldn't remember it. To Cal, it's important that we remember his birthday because it carries great weight in his life-- after all, he has had two birthdays, he says, and is anticipating one more as he writes the book.
In connecting his family's history to world history, Cal reprises a theme of the book: self-importance. He allows their personal events to overshadow the greater weight of the historical events themselves. All in all, it's akin to name-dropping, as he uses these dates to make himself seem more interesting and at the center of things.

-Taylor