"A couple's husband has double eyelids, his wife has single eyelids, and the first child has single eyelids", indicating that the single eyelid is recessive, the double eyelids are dominant, and the father's genetic component is heterozygote. The gene map is as follows: "Later, my wife underwent plastic surgery and became a double eyelid", which is a variation caused by environmental factors, and the genes controlling eyelid traits have not changed ... From the gene map, "If they have a second child"