Let us suppose for a moment that you are correct. Even if you are correct, this does not mean that people **automatically** forgive as if this is some kind of an instinct. People still have to:
- cognitively understand that to forgive is to be good to those who are not good to them;
- decide to appropriate forgiveness, making it a choice, not an automatic response;
- struggle to forgive. It takes effort and even some pain to be good in this context;
- understand that there are no guarantees from the other that reconciliation will occur and occur well.
Do you see that to forgive still is something that is slowly formed within a person as good, comes out as a heroic choice, moves forward as kindness toward others, and is done even if it will not lead to others stopping their destructive behavior? If you see this, then what words other than “moral virtue” would you use? If this only is an evolved biological mechanism, then why do so many people not understand what forgiveness is and refuse to forgive? It seems to me that if forgiving were an evolved biological action, then we would see more people engaging in it and without such a struggle to complete it well.
For additional information, see: What is Forgiveness?