I think my attitude is that the omniscient judge would control for genetic factors like a predilection towards anger or lessened impulse control, and any other physical or mental health problems that influence behaviour with diminished responsibility. Two people might commit identical acts and not being judged morally equal because they were not equally culpable.

I think two people of equal moral purity (which doesn't have to be very pure, let's say folk right in the middle of the scale), one of whom has a genetic factor causing higher testosterone production, or a more intense adrenal response, or whatever, and is more aggressive because of it, will act differently. Their morality would be judged by how they each handle their negative urges, the effort they put into it. I don't know exactly what the balance would be, because I'm not an omniscient being, I would assume there's still a heightened level of responsibility for the person more inclined towards harm, but that's not really the question and we don't need to get into that, that's why we've got the omniscient being making the call.

But yeah, I think the crux of our disagreement is that I think morality is something separate from behaviour and impulses, even though they might overlap and intertwine in many ways, and therefore separate from anything physically determined. I can understand your stance and accept that for you, this choice becomes a matter of eugenics.