The first reason is that human genes are different. We emerged in the world through genetic recombination of both parents, so that is to say, all our characteristics are determined by heredity. The length of human limbs will be different because of the role of bones, so the ears will be different because of genes. Some people have large earlobes, while others have small earlobes. According to the continuous progress of scientific research, the organs in the body are actually related to parents' genes.
The second reason is that our acquired habits are different. We all know that India has a habit of wearing collars, which directly leads to their long necks, because everyone has to wear long collars. So it also shows that a person's acquired habits can affect our organs, so some people say that newborns should pay attention to their sleeping position when they are born. In fact, these traditions are not unreasonable.
The third reason is that everyone lives in a different climate. We are in different regions, and the climate is different, which affects the appearance of people in different regions. In the cold climate area, we will find that their noses are very big, which is to adapt to the self-regulation of living things.