Genetics significantly influences an individual's fitness potential by determining factors such as muscle fiber composition, metabolic rate, and response to exercise. Genetic predispositions can affect how easily one gains muscle or loses fat, thus impacting overall fitness performance. For instance, some individuals may naturally excel in endurance activities due to a higher percentage of aerobic muscle fibers, while others might be predisposed to strength training. Understanding one's genetic background can help tailor fitness programs for optimal results, allowing individuals to make informed decisions about their training and nutrition choices.