This is sort of off-topic for this thread, but I'm not sure how you can make such a blanket statement of something that is very hotly debated in the sociological and psychiatric field. There certainly are people who have spent their entire careers researching this.
I have to say I'm about 100% in the "nature" category. I think we come as we are, with our inherited destinies intact. Identical twins separated at birth usually end up in virtually the exact same place in life - even if their beginnings were very different. The greatest determiner of criminality in a son is criminality of the father, regardless of whether the son ever knew his father or ever knew the father was a criminal, and the boy was adopted out at birth.
I fully believe that we inherit, genetically, almost everything we become. Especially boys.
We shall agree to disagree. As my sig says, it's my opinion. It is however, based on a lot of education and a lot of life.
Also, often times identical twins who are raised together end up very different because they strive for originality. It is a balance of nature and nurture, but I do believe that in all but the most extreme cases, nature can be overcome and is.