If anybody has published evidence of genetic factors in racism, I have not found them.
Every complex behavior is, however, accomplished by the anatomical substrate mediated by physiological processes, and therefore, created according to genetic instructions, including. So, I wondered, what mechanisms enable racist behavior?
Social discrimination depends first on cognitive discrimination/discernment of differences and social categorization/classification in the context of value judgment.
We see, we categorize, we judge, we act
What evolutionary imperatives required those behaviors for which we must infer a genetic basis?
Social animals are social, territorial, and compete for mates.
Therefore they must denote differences in terrain, identify an area suitable for nest building and offspring-rearing, and defend that territory as needed, for of survival of the group and the species.
They must denote inter- and intra-species differences to identify possible threats to territory or family and possible mates and/or allies in the struggle to maintain territory.
If a threat is detected, the fight, flight or flee distress response is triggered and the appropriate evolved behavior is activated.
If an intraspecific individual is detected, affiliative behaviors are triggered, and an allyship is activated.
If a potential mate is discerned, courting behavior is initiated and mating becomes possible.
Hence, the biological mechanisms required for racism to be enabled are the same as those territorial and mate selection processes humans have evolved. The appropriate behaviors for each situation, however, have to be learned in humans and will depend upon the value judgments promulgated by respective socio-cultural environments of all individuals in a social-animal interaction.