Single eyelid and double eyelid are commonly known as dragon and phoenix eyes in medicine, and male and female eyes are also called big and small eyes. "Singles and doubles" are determined by genes. "Single pair, the gene should be dominant, and the gene composition should be double eyelids. It is possible that one eye is a single eyelid and the other is a double eyelid, because the development level of levator palpebrae muscle fibers in the two eyes is different. Hereditarily, single eyelid and double eyelid are controlled by a pair of alleles located on the autosome. The offspring of single eyelid and single eyelid are all single eyelids, and the offspring of homozygous genes are all double eyelids. The offspring of heterozygote double eyelid gene will have binocular separation, which can be corrected by double eyelid surgery. But you must go to a regular hospital and choose the right double eyelid plastic surgery. Most beauty lovers with single eyelid and double eyelid can choose double eyelid plastic surgery. Anyone who asks for double eyelids can be a double eyelid surgery. People with long eye fissure, thin eyelid skin and high nose bridge have better surgical effect. If one eyelid is a double eyelid and the other is a single eyelid, the operation can make both sides symmetrical on the basis of one side of the double eyelid.