Do humans come with morals/ethics "built-in" to them, or do they gain them through sensory stimulation?

I think we have a natural sense of morality. This stems from humans evolving from community animals. Community animals rely on members of the pack to behave in a manor that enhances the wellbeing of the pack. Individual pack members that work well in activities such as hunting, defending the pack and raising offspring, get the opportunity to breed and p along their good genes. On the other hand, individuals that are anti-social, overly aggressive, or otherwise harmful to the wellbeing of the pack are driven off or killed and do not get a chance to p along their bad genes. Millions of years of this process has given us an instinct to be good community members. We call this instinct our conscience.