Which of the following is not a factor influencing growth and development?

The correct choice is based on the understanding that hereditary factors, environment, and nutrition all play significant roles in influencing growth and development. Hereditary factors refer to genetic influences that determine physical characteristics and potential health risks passed from parents to offspring. The environment encompasses a wide array of external influences, such as socio-economic status, access to healthcare, and living conditions, which can greatly impact a person's development. Nutrition is another critical aspect, as the availability and quality of food directly affect physical health and growth potential.

In contrast, age of onset, while relevant in some contexts, is not a primary factor in general growth and development. It generally refers to the timing of certain developmental milestones or conditions rather than a direct influence on the growth and development process itself. Thus, choosing "age of onset" reflects an understanding that it does not inherently affect growth and development in the same fundamental way as hereditary, environment, or nutrition do.