The United States has a one-drop rule with regard to who’s black: even one drop of African ancestry makes someone African American. But the one-drop rule is missing in Brazil. That’s the story, anyway. But in reality things are more complicated. In the United States, according to a recent Pew survey, most whites and Hispanics actually think of Barack Obama (white American mother, black African father) as mixed, although most African Americans think he’s just black. And in Brazil (at least in Bahia) I found that many people follow a weak one-drop rule. People I interviewed overwhelmingly stated that the child of a white man and a black woman, or a black man and a white woman, would belong to some mixed race category like moreno or mulato – so no strong one-drop rule. But on further inquiry, many people said that two mixed parents could more easily have a black child than a white child. My interviewees were more likely to say that a black and a mixed parent could have a black child than that a white and a mixed parent could have a white child. And they were more likely to say that two black parents could have a mixed child than two white parents. The consistent theme here is a weak one-drop rule: while mixed race individuals are not simply classified as black, they are treated as closer to blacks than to whites in their hereditary potential.
Why some Brazilians buy into the weak one-drop rule is unclear. Is black ancestry seen positively, as stronger than white? Is black ancestry seen negatively, as an impurity that can’t be erased? (Note that the pattern described above is not consistent with a theory of recessive and dominant traits, nor did anybody bring up this possibility.) These are topics I hope to address in future research.