In the story, Phoebe considers herself American while her grandfather views her as Greek. What contributes to how someone views themselves?

According to a different source, this question refers to the story "Blue-Sky Home" by Lisa Papademetriou.

In this story, Phoebe is half-Greek, but she was born in America, and she does not consider herself to be Greek. However, her grandfather considers her to be Greek. The main factor in this is the fact that Phoebe is not acquainted with Greek culture. What contributes the most to how someone views himself is the cultural practices that they grew up with. If someone follows particular culinary or religious practices and celebrates traditional holidays, it is more likely that the person will feel identified with that culture. Other factors can include being fluent in the language of the place, or visiting this country regularly.