Which of the following is a factor that can influence individual sensitivity to chemicals?

Heredity plays a significant role in influencing an individual's sensitivity to chemicals. Genetic factors can determine how a person's body metabolizes and reacts to various substances, including those found in cosmetic and personal care products. Certain individuals may inherit traits that make them more susceptible to allergic reactions or sensitivities, leading to skin or respiratory reactions when exposed to specific chemicals.

Other factors, such as changing jobs frequently, having a pet, or living in urban areas, may affect exposure levels to chemicals or stressors in the environment, but they do not have the same direct influence on biological sensitivity as hereditary traits do. Understanding the influence of heredity can help cosmetologists and health practitioners anticipate potential reactions in clients and take necessary precautions during treatments.