I think the degree of guilt that we feel results mostly from the way we are conditioned when we are young. So if somebody was conditioned to believe that nothing they did was wrong then they would be unlikely to feel guilt when they were older.
Someone like this probably wouldn’t be much fun to be around though!
Not sure this is really my field as I am a materials scientist.
Most of our emotions have evolved over time to give us (as a species) some kind of advantage. Guilt is one of those emotions and appears to be useful for us to live together in a society. WIthout it there would be fewer inhibitions and fewer reasons not to do bad things and society would perhaps not work in the way we experience it now. It is our ability as a species to live in supportive societies that has allowed us to be so successful on earth.