Purpose: The scientific knowledge of how genes affect disease expression and evolution can facilitate more effective environmental and drug therapy interventions delivered by health care professionals. The purpose of this paper is to a) describe the role of genetic science in healthcare; b) explore genotype determinants for environmental and pharmacological interventions; c) and analyze ethical dilemmas, barriers to access, and allocation of resources based on genotype. Methods: A review of literature was conducted from the disciplines of nursing, medicine, psychology, and sociology using the CINAHL, Ebsco Host, Medline, and PsychINFO databases. The search was limited to peer reviewed, full text article in English that dated from 1987 to 2011. Inclusion criteria were articles describing environmental, pharmacologic, and nutritional influence on genetic expression. Forty-five articles on genetic intervention were chosen for further review, in addition to five book publications which met inclusion criteria. Many of the sources retrieved were obtained from the biomedical sciences and published in the last decade, owing to more recent innovations in genetic discovery. Results: Disease and treatment must be approached according to genetic profiles for effectiveness and to increase health outcomes. Several variations were found regarding response to pharmaceuticals, as well as environmental exposures, based on genotype. Conclusions: Health care has been practiced using a "universal protocol" approach; however, as the literature reveals, each individual genotype must be taken into account to provide optimal care.