Why do people grow blond hair?

I just read a related article in a book beforehand. I'm not sure that the color of human hair is determined by the proportion of three pigments in hair. I seem to have forgotten which three. What I know is that most of the yellow people's hair is black, because we live in the subtropical region and receive sunlight all the year round, and there will be more red melanin in our hair than others, so most of us are black. As for why you have blond hair, I have several explanations. First of all, you dyed it ... this is definitely a reason. Second, it has something to do with your living environment. If you often live in a humid or sunless environment, there will be more yellow pigment in your hair, resulting in a few blond hair without more red melanin instead of yellow pigment. Europeans and Americans have made progress because of the environment in which they grew up, and the pigment in their hair is mainly yellow. Third: It has something to do with your biological parents and your genetic inheritance. After all, people are constantly evolving. Maybe people around you don't have this kind of reaction, only you do, so only you can cause different hair colors under the influence of mutant genes. Don't think about why it's you, a few percent of the world's 6 billion people, but you just can't see it. Fourth: eating habits, abnormal eating habits will have a certain impact on hair. The lack of nutrition and vitamins in the community every day will lead to yellow hair and reduced pigment bands. This is what I read in a book. I'm not sure. But the landlord can rest assured that this can tell you some questions. As long as you move out at your own pace, correct your wrong living habits and live a healthy life, you will be fine.