When Dalton was young, he was laughed at and ridiculed by other children because he mistook the red uniforms worn by soldiers for green uniforms. When he grew up, Dalton, who was diligent in observation, was fascinated by geranium flowers: it was sky blue in the sun during the day and turned bright red at night.

But when he told this to several friends, they observed and pointed out a fact that shocked Dalton: geranium flowers are pink, not sky blue or bright red! Dalton thought of his mistakes in color discrimination when he was young, and immediately suspected that his color vision might be damaged. After careful study, he finally found his own defects in color vision. It turns out that the red in normal people's color vision is almost scarlet in his field of vision. 1894, Dalton published a paper, which described the phenomenon of color blindness in detail and systematically for the first time.

Color blindness exists on the X chromosome.

According to the research of modern genetics, the genetic mode of color blindness is sex-linked inheritance. It turns out that sex chromosomes in human cells are divided into X chromosome and Y chromosome, among which XX chromosome combination is female.

The XY chromosome combination is male.

. However, human colored genes exist on the X chromosome, but not on the Y chromosome.

According to Mendel's genetic law, because color blindness gene is recessive gene and normal color width is dominant gene, women with normal color vision may have recessive color blindness gene. If both parents are normal color vision genes, then the offspring will not be color blind; But if both parents have normal color vision and the mother has recessive color blindness gene, the offspring may have normal color vision or color blindness. For a woman, if she is color blind, then she must have two identical recessive genes at the same time, but such opportunities are rare after all. Men have only one X chromosome, so they are much more likely to suffer from color blindness. No wonder male color blindness patients obviously fuck more women. Color-blind women should choose to have girls.

Interestingly, men's color blindness genes are always passed on to their daughters, and then passed on to their grandchildren through their daughters. Therefore, for a male color-blind patient, if he wants his offspring to get rid of the painful entanglement of color blindness, he should not only marry a normal woman, but also choose to have a boy.

. For a woman with color blindness, not only should she marry a normal man, but she should also choose to have a girl.

In a word, color blindness, as a genetic disease, does not directly endanger people's lives or cause physical disability like some genetic diseases, but after all, it has a certain impact on patients' career choice and physical and mental health, and is also unfavorable to the improvement of population quality. Therefore, the harm of color blindness should not be underestimated.