Genevieve is pretty good at making excuses, but for herself and other people. If put to the screws, or even just a really probing interrogation, she would probably say that she is what her environment made her--even if it's only because it's easier for her to see the direct cause and effect there. She knows people in organized crime--therefore she takes up a life of crime and easy money. In some ways, her upbringing was violent (I don't really elaborate on that, but it's something I want to reveal slowly) so she finds violence a little easier than most.
But on the other hand, she also acknowledges that these were and are choices she had made and more than likely will continue to make. One of the things I think is more compelling than environment for her, however, is biology--in the sense that, biologically speaking, she sees herself, and the world around her sees her, as very young. And she always will be. She is female, and Immortal; those things are simply how she is. And those things, I think, are what makes her feel more resigned to the choices she makes.
The disturbing thing about her is that she habitually tries to use situational ethics for people whose situation isn't quite like hers. She can find reasons for anyone's behavior--Methos', even Kronos', because she still desperately wants to believe there's good in everyone, and that there are reasons for things. Although she likes to think of herself as impulsive, and not a very deep thinker, the truth is, she's fairly analytical in her thinking--things ought to have patterns, ought to make sense. Cause should precede effect. If someone is *bad*--there must be a reason why.
But she also tries to reassure herself that people don't change because her one, real, horrible fear is that she will change--and not for the better. Deep down, she is certain that the life she leads will erode what's left of her morality, and she will end up like Kronos--at a level of amorality nearly impossible to differentiate from insanity. She would like to think she can hold on to the human side of herself, and not become monsterous. That a change may be for the better still hasn't dawned on her--and Methos, really, despite any *change of heart* he's ever had, doesn't serve as an example to her. Her impression is that the two of them "think alike"--i.e., he does whatever he has to do to survive, same as she does. Which is why she presumes that his ethics probably got formed the same way she imagines her own did.
Is change possible, though? Truth is, Genevieve is changing and has been from the moment she found out that Kronos was dead. She is nowhere as morally challenged as she could be (as she is in my AU). She just doesn't see it because it's happening to her. But she is becoming more aware of her choices and tries, more often, to base them on what is right, not what she wants.