In the article it was talking about a court case, in the case a man was being convicted for murder, but it was changed to be a charge of voluntary manslaughter. It was changed to this because in genetic testing they found a MAOA gene, known as the warrior gene. This gene can make you more antisocial, and can cause impulsive, aggressive behavior. The doctor found that with the MAOA gene, and his background of abuse as a child, left him at a greater risk of violent behavior. They then start talking about how this is new technology, and it is vulnerable to being manipulated in court. Going on to talk about whether or not using genetics in court is as influential as some believe. Taking in account his upbringing, they think that the abuse was more influential in his aggressive behavior, so it is hard to tell what the genetic role is in the case. Also, in other cases the genetic factor made no different on the person's sentence. It is up to the judge on whether or not they think that the biology is a factor in the case.
The warrior gene is relevant in this case because it made his sentence at least 15 years shorter. Because he had the MAOA gene, he was convicted with voluntary manslaughter, which is a 10 year or less sentence, and murder is a 25 year minimum sentence. Since his reaction was out of the norm, his defense team asked for a scientific assessment, and that's how they came across the warrior gene. Because they find that this gene makes people more aggressive, and impulsive, that is enough of a reason to let courts change the charge. I think that just because someone has a genetic difference doesn't mean that they should be tried any differently. Obviously there is something wrong with the person if they're just randomly killing people they're friends with, so why should they get out of jail any sooner than someone who doesn't have the MAOA gene. I think if they're going to change a charge over something, it should be more focused on background of the person (like abuse) rather than a gene.