Final answer:
Differences in traits like hair color are primarily the result of genetic variations. While the environment can influence gene expression, the genetic code determines these traits. Linked traits and population genetics contribute to the diversity seen in human characteristics.
Step-by-step explanation:
The differences between people that cause one person to have red hair, for example, and another to have brown hair are the result of c) Genetic variations. The molecule DNA is responsible for the inheritance of traits. DNA contains genes which are segments that determine specific traits such as hair color, eye color, and height. While the environment can influence how genes are expressed, the primary differences in traits like hair color are determined by the genetic information passed down from parents to offspring.
This genetic information can vary greatly between individuals leading to the diversity we see in traits among the human population. Although environmental factors can affect the way genes are expressed, such as through sun exposure, which affects skin color, or nutrition, which Furthermore, specific traits can be linked, which explains why hair color and eye color are often inherited together.
For example, individuals with blonde hair often have blue eyes, and those with brown hair often have brown eyes. Moreover, as humans spread across different regions, genetic characteristics diversified, resulting in the variety of skin, hair, and eye colors seen today. Although environmental factors can affect the way genes are expressed, such as through sun exposure, which affects skin color, or nutrition, which affects height, the underlying genetic code is the primary cause of the observable differences in traits such as hair color.