Melanin is one of the most expensive substances in the world. But there are two types of melanin and each is produced by different genes.
Eumelanin is responsible for black and brown shades. Pheomelanin produces red and yellow shades. The gene that produces melanin was totally lost in humans who evolved in northern, sun-deficient climes as a matter of survival to retrieve enough vitamin D, about 30,000 years ago, and at the same time the gene for pheomelanin appeared in the same populations. Eumelanin died out in northern climates.
White people do not lack melanin- albinos only do- they just have their own. Except with migration and intermingling of populations, many people know have both genes! For example fair hair,skin and brown eyes.
A saturation of Eumelanin gives a very dark skinned individual with black hair. A super saturation of pheomelanin gives you a ginger.