Children as young as three had already learned to prefer whiteness
Psychologists Kenneth and Mamie Clark showed Black children four dolls, identical except for skin color, and asked which was nice, which was bad, and which they'd like to play with. Most picked the white doll as nicer, showing that racial bias had already taken root before school age. The findings became part of the evidence in the US Supreme Court's 1954 Brown v. Board of Education ruling against school segregation.