Editor's note: Ruben Navarrette Jr. is a CNN.com contributor and a nationally syndicated columnist. CNN's Defining America project is exploring the stories behind the numbers to show how places are changing. This week, get to know more about your neighbors all across the country -- how they live and love, what they believe in and how they came to call themselves Americans. The week will culminate with a Secret Supper in New York City, and Eatocracy invites you to participate online starting Monday July 11th at 6:30 p.m.
San Diego, California (CNN) -- I'm in a mixed marriage. My wife is Mexican and I'm Mexican-American.
You might think there isn't much of a difference between the two, but you'd be wrong. We share the same ethnicity, but we were born in different countries. That makes all the difference. Our story is a reminder of just how complicated cultural identity can be in this country.
According to the 2010 census, about 50.5 million Latinos live in the United States, accounting for 16% of the population. About two-thirds of that 50.5 million -- or about 34 million people -- are Mexican or Mexican-American.
It's no secret that there are divisions among Latinos. Mexicans and Mexican-Americans have little in common with Cuban-Americans, Puerto Ricans, Dominicans, Brazilians, etc.
But what isn't often talked about is the less noticeable chasm between Mexicans and Mexican-Americans.
Well, it gets talked about a lot at our house. My wife is a legal immigrant who came to the United States as a child and went on to become a U.S. citizen. But, at heart, she considers herself Mexican. You can take the girl out of Guadalajara ...
For my part, I'm a Mexican-American Yankee Doodle Dandy. Born in Fresno, California, to parents who were also born in the United States, I view the world with the eyes of an American.
Even our taste in food is different. She could eat Mexican food every day of the week, while I'm just as partial to hamburgers and hot dogs. And when we do settle on one kind of food, there are still cultural variations in how it's prepared.
Growing up, my idea of what a taco looked like was a hard shell, meat filling, lettuce, tomato and cheese. My wife would have none of that. For her, a taco is a small corn tortilla with meat, onions, and cilantro. Anything else is uncivilized.
But where the cultural divide really becomes clear is when I try to transfer my values and worldview south of the border. Climbing on my soapbox, I've been known to say things that my wife contends are utterly naive and ridiculous.
For instance, when Mexicans complain about a corrupt government, I'll become Jeffersonian and say: "Well, why don't people just organize and replace it with a government that works better?" My wife will shake her head and say: "You're such an American. You think anything is possible, and that change is easy. This is Mexico. People there have no power."
I'm not alone. I have a friend, also a Mexican-American, who was for a time married to a Mexican woman. He told me similar stories. Whenever he would say something that made him sound like the quintessential American, his exasperated wife would ask: "Exactly what part of you is Mexican again?"
Ironically, long before I met my wife, while growing up in central California, I never considered myself anything but a Mexican. Not a Mexican-American, but, in ethnic shorthand, a Mexican. Just as important, it was how others saw me and people like me. Adults referred to the "Mexican" part of town or talked about the high school's first "Mexican" quarterback or first "Mexican" homecoming queen.
Years later, when I was admitted to Harvard, jealous white classmates informed me: "If you hadn't been Mexican, you wouldn't have gotten in."
Not Mexican-American. Just Mexican.
My readers do the same. Not long ago, one accused me of welcoming the "Mexican invasion ... because you're Mexican."
OK, so I'm Mexican. Just like my friends in Boston who call themselves Irish, and friends in New York who call themselves Italian, and friends back home in Fresno who refer to themselves as Armenian.
Cool. I'm Mexican, right?
Wrong, says my wife. Wrong, wrong, wrong. To her, I'm an American, plain and simple. Born and raised in the United States, how could I be anything else?
She's the Mexican. She came to the United States with her mother and three sisters when she was 9 years old. Later, she returned to Mexico for two years of high school, and she stayed there for four years of college before returning to the United States for graduate school. In addition to being fluent in English, she speaks, reads, and writes Spanish with an awesome proficiency that I could never attain.
"How can you be Mexican?" she asks. "If you went to Mexico and identified yourself that way, people would laugh. They'd ask where in Mexico you were from, and they'd expect you to answer in perfect Spanish with no accent."
She's right. It's like the old saying that a Mexican-American is treated as an American everywhere in the world except America, and as a Mexican everywhere except Mexico.
I wasn't born in Mexico, she points out, and neither were my parents. My grandfather came from Chihuahua legally during the time of the Mexican Revolution, but he's the only one of my grandparents born south of the Rio Grande. The other three grandparents were all Tejanos, Texans of Mexican descent.
But I've spent my life feeling too Mexican to be 100% American and too American to be 100% Mexican.
This identity crisis is an old story. For the most part, Mexican-Americans -- and there are about 20 million in this country -- aren't sure who or what they are. I would bet that most of us see ourselves primarily as Americans. And yet there is always something out there to make us feel like second-class citizens. Like, say, the state of Arizona.
Sometimes after a discussion where my patriotism is showing, my wife will throw up her arms and say: "And you say you're Mexican. What kind of Mexican are you?"
I always respond: "The American kind."
The opinions expressed in this commentary are solely those of Ruben Navarrette Jr.