The sex chromosomes of human body include two kinds of chromosomes: x chromosome and y chromosome, females have two x chromosomes, and males have one x chromosome and one y chromosome, and the presence of y chromosome is a sign of maleness. If there is a genetic abnormality in the y chromosome it will result in y chromosome genetic diseases, these diseases include ectopia polymorpha, duckweed disease, arrow pig disease, etc. Since there is only one y chromosome, there is no difference between dominant and recessive genes. Since a son’s y chromosome can only come from his father, the inheritance is characterized by the presence of the disease-causing gene in the father, all the sons develop the disease, and the daughters are healthy.