This is very Kantian and precisely what I hate about Kantism. "He should do this for this reason, not for that feeling, and he should stay away from doing it for that consideration and not because of his fear or his urges."
This is f-u-c-c-ed. I am with Hume who said humans operate on the calling of their passions, and the intellect is a tool to fulfill their passions' call.
I'm going to ignore the Kant references because I'm not basing any of my views off of his work.
If I am a jealous man, I will think in jealous terms. You are not, however, informed at birth of how that jealousy shall manifest itself. It can't be predetermined that I will be jealous of people with wealth because the concept of wealth is learned. As a jealous man, I can't be jealous of people having things I don't think I'm deprived of or things that I see as low in value. If you know a man to be jealous, do you know how he will treat those of whom he's jealous? Do you know where or to who his frustrations will be directed?
No, you do not, that is because these are things which will be decided through interpretation and habit.
If I'm a competitive person, is that because of reason or biology? Biology. If we're both competitive and I hold charisma as being this awesome thing which everyone should think is important and it's not even on your radar as being something you care about. is it biology that makes me competitive about charisma or is it reason and interpretation? The latter.
The breadth of opportunities for channelling "passions" through interpretation makes it worth exploring options.
Not wanting to kill others is clearly a biological impulse that can't be removed by justifying it rationally. "One should reject violence on a moral or logical basis.. also reject the reasons for committing murder like jealousy, greed, hatred" is what I said in response to "Murder is hard for non-nut jobs (as it should be)". So I am not trying to talk as though everyone has a blank slate opinion about violence and people should choose good reasons for not wanting to do violence. I agree that's mostly biologically determined.
You can still, however, reject violence on a moral or logical basis rather than because of your lack of proclivity towards violence. You can still reject murder by arguing against the reasons for murder, rather than because, you're not the type of person who would ever think about killing someone. There's a functional difference between rejecting something on an interpretative basis rather than surrendering yourself to your biological proclivities.
OP has made choices, possesses interpretations and believes in what he believes in, all of which was necessary for him to come to his conclusions. Changes made to those things through reason will make a meaningful difference.