My 87-year-old grandmother has a very specific way of saying the word black: she drags out the a and makes the k extra hard for an effect that drowns the c. “Blaaaak” out of my grandmother’s mouth is an admonishment, not a color. “Blaaaak” out of my grandmother’s mouth travels a step beyond being a pejorative to having the hair-raising resonance of a word that damns as well as describes damnation itself.

“Blaaaak” out of my grandmother’s mouth is a curse.

But the freckled, fair-skinned black woman who helped raise me doesn’t use “Blaaaak” to refer to people’s skin tones. Though such attitudes are often mistaken for a bias against darker skinned people of our race, the assumed colorism of older African Americans is more often a reaction to the humiliating and degrading representation of dark skin in images used to depict and reinforce black people’s sub-human status in the late 19th and first half of the 20th century.

But it wasn’t until a month ago, and seven months pregnant, that her own granddaughter came to understand that distinction.

My mother and I had gone to pick out a cake design for my baby shower, and the one I liked had a pile of leaves in the middle where a plastic portrait of a lily white baby’s face blossomed. I asked if they had a black baby face, and my mother even asked if they had a “tan” baby (since my husband is white and our child will be biracial), but the sales woman told me that their babies only came in black and white. So I chose another design – one that included a black baby.

I didn’t ponder this particular bakery’s limited selection, the persistence of that fictional racial dichotomy, or even kick myself for not taking our business elsewhere. That is, I didn’t question it until later in the day when my grandmother asked about the cake and I explained that it would have a black baby.

“Did you choose a Sambo-blaaaak baby?” she asked.

The plastic figurine’s dark blue-black skin and light pink lips flashed in my mind. “Well, kind of,” I answered.

My grandmother lost it:

“Are you crazy? Oh, you must be! Do you think I’m going to eat a cake with a creature from the blaaaak lagoon on it?! Didn’t they have brown skinned babies? Didn’t they have Puerto Rican babies? Didn’t they have anything other than Sambo-blaaaak babies?”

The word “sambo”, and the caricature attached to it, has a multinational history – from its use in Latin American Spanish to refer to a person of Native American and African heritage, to the overseer in Harriet Beecher Stowe’s Uncle Tom’s Cabin, to the children’s book The Story of Little Black Sambo in which a South Indian boy tricks a gang of hungry tigers. But my grandmother wasn’t thinking of India or how the geography of the slave trade shaped racial terms. For her, “Sambo” recalls the blubber-lipped, blue-black caricatures of African American children known as piccaninnies, perched on dilapidated porches, half-clothed and dusty, and as happy in squalor and ignorance as they can be.

Depictions of black people, like Sambo, the piccaninny and many others, were manufactured and sold to the public – often to sell consumer products – as foils for whiteness. The scholar Henry Louis Gates Jr even calls what he terms “the everyday racism of American popular culture “Sambo Art”. Everything these imaginary “mascots” of blackness were scripted to be – slow-witted, indolent, greedy, grotesque – white people and white children were supposedly not.

So when I chose a black baby for the cake, my grandmother justifiably wondered who the hell I thought I was and who exactly I was setting up my child to be. The truth is my grandmother’s response prompted me to ask myself these same questions. And the answers surprised me.

In one regard, my ideas about race are more retro than my grandmother’s. I picked a black baby to represent my mixed-race unborn child because of my automatic adherence to the “one-drop rule” – meaning that, because I am black, my child will be too, as was the case during slavery and Jim Crow. But my grandmother’s irate questions about why the bakery didn’t have babies of many colors acknowledged the truth that runs in all of our veins: race is a spectrum, not dichotomy.

According to the 2010 Census, the multiracial American population grew by 32% since 2000. And though 2000 was the first year people could check multiple race boxes on the census, between 2000 and 2010 the number of Americans who identify as both black and white increased 134% to 1.8m. The 2010 Census also reported that racial and ethnic minorities made up nearly half of the under-5 age group and were soon going to be the majority.

The biracial baby boy I am carrying will be a part of this multiracial wave entering America’s schools and more broadly American life. Yet, despite my child’s mixed-race heritage, I found it unthinkable to put a white figurine on my baby shower cake. But just as “blackness” has come to mean something different over the generations since my grandmother was young, so whiteness will also come to be less definitive – and ultimately less proscribed, given the census numbers and the heterogenous reality they reflect.

In the end, despite the fact that I am not having twins, I chose one black baby and one white baby to preside over my cake. Just as, with each coming decade, more people will check more than one box to describe their own racial identity – including quite possibly my child – I decided it was more emotionally accurate to identify my baby as both, rather than one or the other.