I won't get into a debate about who is a better authority on this, but I would invite you to ask any clinical psychologist (which I will point out that Neuroscientist is not) if you can diagnose APD through a brain scan, they will unconditionally tell you no. There may be some correlations they can find regarding brain and behavior, but it is by no means conclusive, nor is genetic predisposition to violent and aggressive behavior. While it is not an either/or situation (it possibly could be affected by both), the evidence of environment causing this behavior is far stronger.
As far as what you debated me on, that is very easy information to find; anyone familiar with psych diagnostics could tell you this:
Individuals with Antisocial Personality Disorder grow up being lawless and impulsive. The core features of this disorder are: (1) antagonism (manipulativeness, callousness, deceitfulness, hostility), and (2) disinhibition (risk taking, impulsivity, irresponsibility). This disorder is only diagnosed if: (1) the individual is at least 18, (2) these behaviors occur at home, work, and in the community, and (3) these behaviors lead to clinically significant distress or impairment in social, occupational, or other important areas of functioning.
In childhood, these individuals usually have Oppositional Defiant Disorder (towards parents and teachers) which develops into Conduct Disorder (delinquency) in adolescence. This delinquency takes the form of reckless thrill-seeking, physical violence (towards people or animals), and law-breaking. These individuals become the school bullies, thieves, vandals, and drug-dealers. Most adolescent delinquents grow out of this behavior as they enter adulthood. However, those that increase their delinquent behavior as they enter adulthood have their diagnosis changed from Conduct Disorder to Antisocial Personality Disorder.
In adulthood, individuals with Antisocial Personality Disorder become more antagonistic. They show an exaggerated sense of self-importance, insensitivity towards the feelings and needs of others, and callous exploitation of others. Their increased manipulativeness, callousness, deceitfulness, and hostility repeatedly puts them at odds with other people.
http://www.mentalhealth.com/home/dx/antisocialpersonality.html
I think you must not have read your DSM carefully; this is from the fifth edition, but I know it is in the fourth also:
Diagnostic Features
The essential feature of antisocial personality disorder is a pervasive pattern of disregard
for, and violation of, the rights of others that begins in childhood or early adolescence and
continues into adulthood. This pattern has also been referred to as psychopathy, sociopathy,
or dyssocial personality disorder. Because deceit and manipulation are central features of antisocial
personality disorder, it may be especially helpful to integrate information acquired
from systematic clinical assessment with information collected from collateral sources.
For this diagnosis to be given, the individual must be at least age 18 years (Criterion B)
and must have had a history of some symptoms of conduct disorder before age 15 years
(Criterion C). Conduct disorder involves a repetitive and persistent pattern of behavior in
which the basic rights of others or major age-appropriate societal norms or rules are violated.
The specific behaviors characteristic of conduct disorder fall into one of four categories:
aggression to people and animals, destruction of property, deceitfulness or theft, or
serious violation of rules.
I work in mental health at a Level 4 prison in Administrative Segregation (the prison within the prison for inmates with life sentences), so you would have a hard time finding anyone more familiar with antisocial personalities than I am.
