Freud and Guilt

So as I was thinking about Freud I thought it would be interesting to have a discussion about his concept of guilt. I know that we talked about it at the beginning of our discussion on Freud but seeing as how he returns to it toward the end of his essay I thought we could as well. It is my understanding of Freud that one's feeling of guilt in regards to an action is a consequence of the super ego's aggression toward the ego (or in other words how the super ego keeps the ego in check). That is to say that regardless of whether or not an action is bad or not morally if the individual thinks it is bad then it is and it produces guilt and even anxiety within an individual.

I think that this arguement is true to a ceratin extent that if someone thinks they have done something wrong even if other do not share their same belief they do experience a feeling of guilt within themselves. Still I wonder if the demands of the super ego are what produces guilt within an individual and the internalized super ego developed as a result of the banding together of brothers who killed their dominant male leader (or patriach) how then did that feeling of guilt come to be in existence?

I know that Freud argues that the super ego developed as a result of the intense remorse felt by those who originally killed their patriach and this feeling of guilt has continued throughout the evolution of men, but why did the guilt or remorse occur initially? Is his arguement that guilt is an inherrent part of human nature? Is it simply that, the aggression that resulted in the murder of the father figure what brought forth guilt? I guess my thought is if they agreed to kill the patriarchial figure why would they then feel bad after they completed the act (remorse) especially if they are driven by aggression and libido?

Maybe I am thinking too much about this but these are my thoughts? Anyone else have any ideas?