Pharmacogenetics is the study of how people respond differently to drug therapy based upon their genetic makeup or genes. Diet, overall health, and environment also have significant influence on medication response, but none are stronger indicators of how you will process medication than your genetics. Pharmacogenetics is the study of how people respond differently to drug therapy based upon their genetic makeup or genes. Diet, overall health, and environment also have significant influence on medication response, but none are stronger indicators of how you will process medication than your genetics. Pharmacogenetic studies have also allowed us to better understand the pharmacology of medications used to treat neurologic and psychiatric disorders.