Question: why do people have diferent shades of skin

Barbara Shih answered on 11 Mar 2015:

There are several genes involved in making melanin (the pigment stuff that make skin and hair dark), and differences in them result in the different amount of pigmentation people have. For instance, a gene called MC1R is responsible telling the cells to produce brown-black rather than reddish melanin, and mutated version in this gene leads to faulty MC1R (in people with light skin and blond/red hair). Asian skin have specific alleles for a gene involved in adjusting the pH within cells that make melanin.