He says the problem lies in your genes.
Genetic diversity is a major contributor to variations in human drug response.
Weber has devoted his career to studying how the small genetic mutations, or polymorphisms, can lead to huge differences in how people respond to drugs. While one drug helps one person, it could have no effect, or even cause harm to someone else. Pharmacogenetics has received a lot of attention as the Human Genome Project nears completion, because it could allow physicians to prescribe safer and more effective drugs and therapies tailored to each patient's unique genetic code. He also discussed a new related field called pharmacogenomics that studies all the polymorphisms in the entire genome. Fortunately, only a limited number affect how people react to drugs or environmental substances.