Man has no moral instinct. We acquire a moral sense, when we do, through training, experience, and hard sweat of mind.
[...] what is 'moral sense'? It is an elaboration of the instinct to survive.
A scientificaly verifiable theory of morals must be rooted in the individual's instinct to survive - and nowhere else!
All moral problems can be illustrated by one misquotation: 'greater love hath no man than a mother cat dying to defend her kittens'
The basis of all morality is duty.