Evolution ingrains community for survival, while war to protect the tribe may also be instinct, however we have grown past war mentally, or at least many have whom realize it is stupid. I don't discount some are susceptible to brainwashing, I see it in an ex friend, but its not just hate/racism/homophobia critical thinking issue, I also saw it in their day to day reasoning skills where they make leaps in logic, that others would prove out.