Why Do We Look Different?

     The primary cause of human phenotypic variety, including variances in appearance, is genetic variation caused by particular alleles, gene interactions, and environmental variables. Despite the fact that 99.9% of human DNA is shared, the remaining 0.1% contains significant variations that result in unique physical characteristics. For example, variances in skin and hair color, especially the presence of red hair and pale skin, which are more common in European people, are associated with variants in the MC1R gene. Melanin is the pigment that gives skin and hair the color they have, and it is produced by this gene. Furthermore, in European populations, the SLC24A5 gene has been linked to lighter skin pigmentation, demonstrating how particular alleles can affect outwardly noticeable characteristics.The growth of hair thickness and texture is influenced by several genes, including EDAR, which adds to the phenotypic variety observed among many ethnic groups.

   In addition to individual genes, populations' genetic architecture is an expression of intricate relationships influenced by evolutionary forces including genetic drift and natural selection. Genetic divergence has historically been encouraged by geographic isolation, which has resulted in different gene pools in different populations. The HERC2 gene, for instance, influences eye color; some variations are associated with blue eyes, which are more prevalent in individuals of European ancestry. Furthermore, as demonstrated by the TYR gene, which controls the production of melanin, environmental factors can apply selective pressure on these features. Because of the preventive benefit, people in areas with strong UV exposure tend to have darker skin. The complexity of human genetics is thereby emphasized by the interaction of particular genetic variations, population history, and environmental adaptations, which is essential in understanding why individuals display a wide range of appearances.

https://www.amacad.org/publication/daedalus/unequal-nature-geneticists-perspective-human-differences#:~:text=Most%20of%20the%20differences%20that,for%20genetic%20differences%20among%20us.

https://www.ncbi.nlm.nih.gov/books/NBK20363/