But I could still say in court that, natural selection produced a genetic trait in me to cause me to be less able to control my violent actions.
You could equally say that gravity produced a genetic trait in you that caused you to be less able to control your violent actions. After all, I hear it's really hard to make babies in zero-G, especially on a planet that's lost its atmosphere to space due to the lack of gravity.
In either case, the justification has to be that the genes actually cause you to have that tendency
. And the science behind that justification does not reside in the realm of natural selection, nor does it reside in the realm of gravitational physics. It resides strictly with the study of human genetics and how particular gene combinations code for particular behaviours
The other theories are just window dressing. Genetics are (supposedly) your enemy here, not other scientific theories, such as germ theory, evolutionary theory, gravitational theory, etc.
Therefore, I should not be wholly responsible for my violent act since I'm subject to this genetic trait.
I've mitigated my responsibility to natural selection, off of myself.
No, you've shifted it to your parents. Not that they could predict your exact genetics anyway. So really, you've just shifted the responsibility to the genes that happened to be passed down in your particular case. Natural selection is a red herring.
You may say this is not a valid mitigation in court, and so would I, but I wouldn't be surprised if people started using such logic, maybe even with some success eventually, since there's nothing specifically in evolution which would contradict such logic.
So, just saying, some evolution in my view could use some updating...
Evolution is off-topic, and unnecessary to such an attempted defense, whether it's valid or not. The key point is whether genes strongly code for the actions in question.
I realize that evolution is a more attractive target for you than genetics are. After all, there are lots of really crazy creationist organizations that are on your side, organizations that are willing to lie about pretty much every field of science in order to promote the idea that the world is 6000 years old and we're all descended from Adam and Eve. In attacking evolution, you gain allies that you wouldn't gain by attackin genetics.
But genetics are really your target here.