Why is quindlen reluctant to define anything remotely resembling a national character

In the text, Quindlen refuses to define anything remotely resembling a national character in America. This is because she believes America cannot be defined in these terms. America is a country that was born out of a combination of people from many different nations and cultures. It is a "mongrel" of a nation. And every person is an equal part of this. Therefore, there is no unified, standard definition of what it means to be American.