I propose 'morality' is not an innate trait but a function of two processes in a human being.
- Experience of pain which generates self-pity
- A feedback loop inside the brain which associates the cause of pain with self-pity
I believe babies get their clue for rewarding behaviour (associated with the neurotransmitter dopamine) in a mild form of violent behaviour called playing. I suppose violence is the first basic instinct that humans get as a surviving technique. Babies basically employ pulling, mangling, biting and hitting. They grunt and clasp their jaws as if their motivating factors. No amount of pleading, painful face making would deter them. Sometimes it only increases their pleasure.
However, when babies are hurt, they want our utmost care. They want our sympathy. In other words, pain generates self-pity among them that they want others to empathize. This is not just about crying at the moment when they are hurt. When the moment is over and pain has subsided they still want us to be attentive to the open wound. Pain is important for the surival in case of injuries, however, on the other hand, it develops a sense of helplessness and thus 'self-pity'.
In my opinion, every person who has felt pain has developed 'self-pity'. Stoicism is a learned behaviour in the adulthood. However, this self-pity to become empathy one needs to have a proper feedback loop in the brain that can associate the cause of the pain with the self-pity. The genetic defects can affect such feedback loop. I'm already suffering from one such impairment related to reinforcement learning.
So a moral individual cannot be moral in every aspect. There could be hardly any instances that an individual experiences all the pains in the world. We need to further expand the definition of a moral individual with this in mind. Since this is not an innate behaviour, a person can grow in morality throughout his life. And the pain need not be just physical. It can be psychological or financial.
A normal moral individual of a set of morals: This person has experienced a set of pains and his feedback loop is alright that he has turned his self-pity into empathy. However, in aspects which didn't cause him any pain he's incapable of empathizing.
A true moral individual of majority of morals: This person has experienced a set of pains and his feedback loop is alright so that he has turned his self-pity into empathy. However, he also has a higher intellectual capabilities or common sense such that he can identify the fundamental nature of the cause of the pain and this would enable him to empathize with other pains caused by seemingly different causes.
But it's possible to make the first type (normal) individual to behave like true moral individual by inculcating empathy thro' education and developing taboos.
People with impaired feedback loop lack empathy.