Some recessive genetic diseases, such as albinism, have a low incidence in the population, but why do these pathogenic genes always exist?

Because it is recessive, many people don't know that they have this gene. Only when they meet people who also have this gene, will they have a quarter chance of giving birth to sick offspring. Three-quarters of the offspring will not get sick, but half will continue to carry this gene. Even if it is a dominant pathogenic gene, the sick person has no choice but to stifle the right to carry on the family line. If someone wants to destroy these people, his ideas, like Hitler's, will be drowned by people all over the world.