Using genetics can be eminently useful. Take a gene that causes a major genetic disease, such as Wilson Disease, where too much copper builds up in a person's system, killing them usually due to organ failure. If someone knows that they are at risk for having children with this, or many other diseases carried on specific genes, they can find out if their child has that disease and, in many cases, help the child live a normal life. When we turn our look to psychology and genetics, however, problems begin to arise. If someone was found to have the gene for "novelty-seeking" or "impulsivity", they will be branded and probably have a hard time getting a job, a home, and healthcare. They could easily become outcasts of society because of one gene that may or may not affect them in an otherwise negative way. In fact, the personality trait for sensation seeking (which could be considered virtually the same as novelty seeking) can be expressed in two very different ways. Both prisoners and firefighters have this personality trait, but what's different is the way they express that personality trait. Mapping personality traits or other psychological traits onto genes and using that information to classify someone will make it much harder for many perfectly "normal" people have a hard time finding a reasonable place in society.