Final answer:
Genetics is the factor that causes differing levels of caffeine tolerance among individuals. Other lifestyle aspects such as diet and exercise can influence the rate of aging, but genetics, which are not modifiable, play a pivotal role in how our bodies respond to substances like caffeine.
Step-by-step explanation:
Due to genetics, we all tolerate caffeine differently. Genetics play a significant role in dictating how various substances are metabolized and processed by our bodies, including caffeine. Factors like enzyme activity, receptor sensitivity, and overall metabolism can be influenced by our genetic makeup, resulting in a wide range of tolerance levels.
The question about slowing the rate of aging does not directly relate to caffeine tolerance. However, to address that, individuals can modify various lifestyle aspects to slow the rate of aging, but these do not include innate factors like genetics. Diet and exercise are examples of modifiable lifestyle factors that can impact aging.