I think it is deeply embedded in the genes.

For between 90,000 and 5,000 odd years (depending on geographical groupings and historical travel paths) that girl's ancestors have endured much conflict and hardship to build and maintain a community with a degree of homogeneity and commonality, quite skilfully avoiding mating with persons from the darker-skinned tribes.

And then one silly girl goes and fucks it all up.

We may not like having those feelings, but they are no doubt there.