Kristal Brent Zook is an award-winning journalist, author of "Black Women’s Lives: Stories of Power and Pain," and a professor at Hofstra University.

Racial identity is fluid, especially for people of multiracial heritage (Bigstock)

A recent Pew study, “Multiracial in America: Proud, Diverse and Growing in Numbers,” has unleashed a flurry of new commentary about a group that’s now growing at a rate three times as fast as the population as a whole. Pew says its numbers have been seriously underestimated by the U.S. Census, which only began offering a box for those of more than one race in 2000. In 2010, those who checked it were 2.9 percent of the population, but Pew now places the number as high as 6.9 percent, with a serious caveat: Fully 61 percent of those with a mixed racial background don’t consider themselves to be part of this “mixed race or multiracial group.”

I can relate.

Although my mother is African American and my father is Caucasian — which I’ve readily acknowledged to anyone who wants to know — the census box I’ve always chosen is African American. To officially consider myself “multiracial” rather than black would be a complicated and, for me, uncomfortable undertaking, fraught with emotional, social, political and cultural minefields.

The box we check, after all, is only half the story. What struck me most about the Pew study was what it called an “added layer of complexity.” No matter which box one chooses, the study found that “racial identity can be fluid and may change over the course of one’s life, or even from one situation to another. About three in ten adults with a multiracial background say they have changed the way they describe their race over the years, it went on to note, “with some saying they once thought of themselves as only one race and now think of themselves as more than one race, and others saying just the opposite.”

Once again, I can relate.

My mother and father were early adapters to the whole multiracial thing, relatively speaking.  I was born in 1965 in Los Angeles, 35 years before multiracial Americans would even have a box. To put the full extent of my uniqueness into context, that was two years before Loving v. Virginia struck down laws banning interracial marriage. Although Pew now puts the number of mixed-race babies at 10 percent of the country’s total births, even by 1970, it was still less than 1 percent.

We were the pioneers, in other words.

And by “we,” I mean myself and my cousin Lisa, who’s also biracial. We were raised like sisters in the same house, along with my African American mother and grandmother. In fact, not even my mother was sure what to call us. She started by telling people we were “half-white” but reconsidered when a family friend asked pointedly, “Which half?” He was white and married to my mother’s closest childhood friend, who was African American.

[Being black is about more than how you look]

My grandmother always explained that we were “mixed” to strangers who just had to know. Now I picture her pressing our heads close to her waist protectively when she said it, as we sat quietly in the pews of Calvary Baptist Church in our best dresses and patent leather shoes.

In the late 1970s, when we were nearly teenagers, being multiracial was still rare enough to be noticed. At Bancroft Junior High School, there were only three biracial kids that we knew of: Lisa, me and Saul Hudson, a shy guitar player who would later become “Slash” of Guns N’ Roses fame. In a rare CNN interview a few years ago, Slash talked about being “mixed.” We went our separate ways after junior high, but I thought it interesting that Slash noted that he and musician Lenny Kravitz were also the only biracial kids at his high school.

Growing up in the beautiful, multi-ethnic chaos of Los Angeles, we were privy to the kind of intermingling and mixing that would later shape the current surge in multiracial numbers.

At Hollywood High School, the popular kids were all manner of minorities and first-generation immigrants: Armenian, Russian, Filipino, Mexican, Guatemalan. Languages spoken included Arabic, Chinese, Korean and Vietnamese. My geometry teacher wore a sari to class and a bindi circle of sandalwood paste on her forehead. I learned later that a Taiwanese friend had married a Cuban girl; that several African Americans had married Latinos. I remember an Armenian friend who’d been tearfully in love with a Mexican exchange student, but what came of that, I never knew. And so on. It was this generation, and the next one, who would become the source of the current surge in multiracial numbers.

With that background, my racial identification as an adult puzzled one high school classmate; I write for publications like Essence magazine, and focus adamantly on social justice issues affecting black women. He even thought to question me outright on this point in a Facebook message not long ago, saying something to the effect that I didn’t “seem so black” in high school.

I’m sure I didn’t. I didn’t have to be. In that environment, I was free to just be.

It wasn’t until leaving Los Angeles for the University of California at Santa Barbara that I was thrust for the first time into a painfully segregated environment, where less than 1 percent of the student body was black. (You can imagine what percentage of this was biracial in 1983. I believe there were two of us.) In this world, I become more “militant” about protecting and projecting my identity. I’d been raised by an African American mother and grandmother, after all. Although my skin was exceptionally light, my grounding and my roots were undeniably black. And I was determined to prove it.

In graduate school at the University of California at Santa Cruz, a white woman who identified herself as being of Italian descent stuttered around for several minutes during a small seminar discussion about race, clearly bothered about something. Finally, she fixed her gaze on me and burst out with what had been eating at her all afternoon. “I mean, when I tan in the summer, I’m darker than she is,” she blurted angrily. “So why does she get to be black?” You can imagine the stunned silence in the room. There’s this twisted perception, among some people, of blackness as a kind of club that only the cool kids get to belong to.

While I can understand the cultural admiration, such Rachel Dolezal-like appropriations can also be deeply troubling — especially when they’re rooted in lies and deceit. Yes, those of us with ambiguous appearances have the freedom to choose affiliations. But to consciously “fool” people is offensive beyond words, perhaps especially to those who live in “fixed” racial realities, unable to shape-shift at the drop of a weave.

[Whatever Rachel Dolezal was doing, don’t call it passing]

“I get to be black, because I am black.” That’s how I remember answering my indignant fellow student. Her outburst was weird, but then so too is a society that places a higher value on black culture than it does on black people. At least my fellow student didn’t show up to class wearing bronzing cream and braids and claim to have a black father.

My evolving race consciousness spilled into my professional life, and fairly quickly, I had a “beat” in journalism, an area of expertise that I hope I’ve contributed to meaningfully for the past 20 years.

At the same time, in my personal life, I’m married to a Madrileño, speak fluent Spanish and live in both New York and Miami. My friends are African American, Caucasian, Puerto Rican, Jamaican, Chinese, Belgian, Brazilian, Haitian, Spanish, Jewish and various combinations of the above. And that’s not to say that some darker-skinned black people don’t also have a wide range of cultural affiliations. Racial identity as others perceive it can be fluid for me, just like the Pew study says, in a way that it can’t always be for darker-skinned Americans. But this “fluidity” is certainly not the same thing as a white person deceitfully posing as black.

I’m acutely aware that my appearance gives me a certain freedom that others don’t always have. And with this freedom — as we always say — comes great responsibility. In my case, that means acknowledging and remaining authentically connected to my roots, even if, for some observers, I don’t appear to be black at first glance.

The increase in the multiracial population is a good thing for this country; a balm to help soothe our battle wounds. And while some now begin to move more and more easily between cultures and ethnicities, I hope that Americans as a whole won’t confuse this fluidity with a so-called “color-blind” society, as ours clearly is not.

As for me, I’ll just keep on checking my own, African American box.