There actually is no definitive answer to this question since Morrison leaves both characters racially ambiguous in order to allow the reader's biases inform the racial identity of each.

As a result, I will argue for both interpretations.

If one were to argue that Twyla is African American, some evidence from the story that one could use includes the fact that Twyla's mother supposedly "dances all night." This could mean that Twyla's mother is an exotic dancer or chronic party goer, both of which one might attribute to a lower socioeconomic status compared to Roberta, whose mother is simply sick. Furthermore, Twyla lives in a gentrifying area as an adult, something else one might use to suggest Twyla is black. The biggest piece of evidence one might use to suggest Twyla is black, however, is when she protests in favor of busing in Newburgh, while Roberta protests against it.

Since busing, a common practice to force racial integration in schools, would largely be supported by black parents, one might argue that Twyla is black just because of the protest side she favors.

However, one could also argue that it is Roberta who is black instead. Twyla tells the reader that her mother taught her to have prejudice toward Roberta's "kind," which could indicate Twyla's whiteness. Another piece of evidence to suggest Twyla is white is that she does not seem to recall Maggie, the deaf-mute woman who worked at St. Bonny's, as being black, while Roberta does. The fact that Roberta calls out Twyla for kicking an "old black lady" when the two were children indicates that Twyla practiced racial violence, at least in Roberta's mind.