Humans are actually petty *terrible* at extending kindness to others who are different from their own group of shared qualities.
Difference creates distance, on an emotional scale, and it is surprisingly easy for humans to not care about people who are different.
It is surprisingly easy for humans to be *cruel* to people who are different from them.
The more difference, the greater the emotional distance, and the easier it is to hurt the other person--easier to exploit and destroy the other.