There is not an exclusionary situation here. While you have both schools of thought on this there is the factor of random or chaos impinging on it as well.
Here is what I mean. Genetics, while a worthy science is still in its infancy. Until they can really read the code like a book to see what is there and not just some specific "words", you cannot use it as a determiner. This is in the case of people.
When you talk about domesticated animals you can use a correlation in that we have selectively bred certain strains of dogs, for example, for "temperament". By continually culling the "bad tempered dogs" you can get a genetically based trait for a "good tempered dog". IE. a Pit Bull vs a Labrador.
People on the other hand tend to take a dim view of having themselves bred for a genetic trait. "Culling" in our society is not being done, outside of the occasional "Darwin Award winner" as we do everything we can to help those who would not otherwise survive without "heroic" measures. (Not that I am complaining about this!!!)
I think that overall, given equal genetic material quality,
MOST would be influenced more by the nurture rather than nature. I do think there are some people in this world that are somehow deficient in that area that makes us a good social critter. In other words there are some blatantly evil people out there. Nothing you can do in te nurture side will have a beneficial effect on them. Fortunately they seem to be a very small aberration given the numbers of the population.
Now there will be many apologists who will blame other factors outside of the individual for whatever act they have committed. The most common type of apologist is the defense attorney. They will blame everything from lack of breast feeding to an overdose of Twinkies for the actions of their clients. Frankly I don't hold much to this "explanation". Each one of those folks made a conscious decision that placed them in some sort of situation that could have been avoided. Even in a "passion" motivated crime there was some trail of events that could have been broken had the offender used the grey matter to better effect.
The end of what I am saying is that I feel each side of this argument has some merit but we know too little to really say with any certainty which is the greater force on the individual. There really needs to be a solid scientific study done, but I am afraid it would be unethical to "experiment" on people like we have done with insects, plants and animals.
Please note for those I lost in this post. Some of it
IS tongue in cheek.
Mav