Final answer:
Genetic variations, gene expression, and environmental factors contribute to the physical and physiological differences between individuals, despite the high similarity in human DNA.
Step-by-step explanation:
Although human DNA is approximately 99% the same for all individuals, there are several factors that contribute to physical and physiological differences between humans. These differences can be attributed to variations in gene expression, which determine the unique functioning and characteristics of different individuals. Environmental factors and experiences also contribute to individual differences. For example, the interaction between genes and the environment can influence characteristics such as height, facial features, skin color, and even the development of certain diseases. Additionally, studies of human biological variation have identified differences in morphology, such as variation in height, jawline, eye sockets, and ear and nose shape and size. Biochemical differences also contribute to physiological variations, such as variations in the sense of smell, genetic mutations that offer resistance to certain diseases, and variations in skin pigmentation in response to UV exposure. In conclusion, while our human DNA is highly similar, the 0.1% genetic difference is still significant and contributes to the physical and physiological diversity among individuals. This genetic variation, along with gene expression and environmental factors, help make each person unique.