(CNN) -- Editor's note: Martha S. Jones is a professor of history, law and Afro-American and African studies at the University of Michigan. She is writing a family memoir on mixed-race identity. This is the second piece in a Black History Month series that explores evolving African-American identity. The first looked at the 'white' student who integrated the University of Mississippi.
My winter 2010 seminar began the way I start every class. I made introductory remarks about themes and requirements for my course on the history of race, law and marriage in the United States.
"Now," I prompted, "let's go around. Tell us about yourself and why you chose this course."
This introduction was routine. But what I heard was anything but the norm: "My mother is black and my father is white." "I'm in an interracial relationship."
Ordinarily, I am silent, listening and taking notes. But by the time I heard a third student say "I am mixed-race, from a mixed race family," I had set down my notebook and was perched at the edge of my seat.
"Me, too," I heard myself say. And with that, I knew that the class would be anything but routine. Until that moment, I had always told a neater story about my identity. I was, simply put, black. And about my mother being white? That had been irrelevant for me and my "one drop rule" generation.
My students had another perspective.
Everything about my family was mixed up. My mother was from the North, of the working class, and a German Catholic who only glimpsed Protestant kids across the lines of East Buffalo's fractured terrain. My father was from North Carolina, a child of the black middle class and a Methodist with a bishop for an uncle who refused to preside over their interfaith nuptials.
They later joked that this difference -- Protestant versus Catholic -- was the ruin of their marriage. But it wasn't. He was black and she was white, and their 1957 union was prohibited by law in North Carolina, where my father was raised.
When they moved our small family from Harlem to a predominantly white suburb, there they met Jim Crow: red-lining, restrictive covenants and recalcitrant neighbors. Once the bomb threats passed, we spent years in awkward isolation.
My parents were social pariahs while we, their three children, were regrettable unfortunates. I don't recall the moment in 1967 when the United States Supreme Court struck down anti-miscegenation laws in Loving v. Virginia. My parents were in the midst of a trial separation, making celebrating our family difficult to do.
But even in sunnier moments, my family rarely acknowledged the social fact of our biracial identity. It was the era of the one drop rule, a view of race that deemed a person with any African ancestry, however remote, to be black.
We were Negroes -- later black, then African-American -- and nothing about our mother's whiteness or our own ambiguous bodies altered that.
"What are you?" schoolmates queried. I can't say that we were asked this more often than other children, but I know that no response elicited more vitriol than the clarification that we were black. The moniker "Casper" (as in ghost or spook) stuck, some backyards were off limits and occasionally fists flew.
Still, we held fast to our one-drop identities.
America largely believed itself organized around a racial binary. It was good to know where you stood, even if it was an awkward fit.
Much of my adult life was guided by the view that, however others might misapprehend me, I was black. And in my circles were friends and colleagues with whom I shared the one-drop identity.
Yes, we had a parent who was not African-American. But that was a quiet fact, one that our bodies might admit but our voices rarely uttered.
Why was that? Perhaps foregrounding a nonblack parent might lead to the charge that we were distancing ourselves from the stigma of blackness. Perhaps we'd be perceived as trying to pass for something that we were not. Perhaps we'd be viewed with suspicion, our loyalties questioned in a world that so often pitted black against white.
Mostly I think we were black because it fit, because it felt right, and because racial identity as a social construction is rooted in more than the fact of one's paternity.
And under the regime of the one-drop rule, I never knew there was an alternative.
Until I had that "me, too" moment in the classroom.
There, I was confronted with student stories that sounded not very different from my own. The mixed race origins of their families had also required a sorting out of identity. They talked about the dynamics of family estrangement but also of love that defied ideas about a color line. They wrestled with social scenes: friendship, dating, and dormitory life where race still seemed to matter. They fretted about checking boxes for college admissions.
But something was different.
As I listened to their stories, it became clear that my students were not adherents to the one-drop rule that had given my generation its place in the national matrix of race.
Yes, they were African-American. This was reflected in their choices of sororities, churches and political organizations. At the same time, they were mixed-race people. Their personal narratives were about lives spent moving back and forth and in between.
And they militantly refused to check just one box.
Our numbers are growing. During the 2010 census, more than 9 million Americans reported that they were more than one race, an increase of 32% from 2000.
It is the possibility that we can be black and be something else that my students urged me to confront.
If I abandoned the one drop rule, who might I be? Both, neither, something else?
Today I agree with my students: All of the above.