The Talmud in מסכת יבמות points out that there are three character traits of the Jewish nation. They are רחמנים, merciful, ביישנים, shy or modest, and גומלי חסדים, they do acts of kindness.
The trait of גומלי חסדים is learned from Hashem’s conversation with Avraham in connection with the destruction of Sodom and Amora. It sounds as if Hashem is talking to Himself when He says that he cannot cover up from Avraham what He plans to do. Because it is obvious how Avraham will educate his children לעשות צדקה ומשפט, to do acts of justice and charity. The Gemara says that this is the source for the Jewish people being גומלי חסדים.
This passage shows the uniqueness of the Jewish people. This explains why when we see cruel and unkind behavior in an individual, we wonder if he’s really Jewish as he does not possess those qualities that typify the Jewish people.