A different skin colour does not cause a lack of empathy:

"A white rat raised among black and white rats rescued rats of both colors. It is not the rat’s color that determines which type of rat it will show empathy for, but the social context in which it was raised. Rats do not show empathy because of similarity in physical appearance.

Empathy can be partial because the experiences of [other] people are hidden, which limits our empathy toward them."

https://www.nytimes.com/2018/12/28/opinion/empathy-research-morality-rats.html