The human genome contains a huge amount of information. Information variability among human subjects is even greater. We are beginning to grasp this genetic variability and its implications for health, behavior, capacities (physical and intellectual), aging, and responses to different types of interventions. Even if still in its infancy, the development of nutrigenetics and nutrigenomics is already providing concrete examples regarding the interaction of genetics, nutrition, and health outcomes whose translation into clinical and nutritional practice begins to be feasible and advisable. This knowledge is instrumental to preventive and therapeutic approaches against nutrition-related disease conditions through personalized dietary choices and recommendations. Importantly, at the same time, the novel knowledge generated is helping to advance our understanding of human biology and physiology.