The pattern of inheritance of familial twins is related to the presence of a previous history of twins in the family of both sexes, and is particularly closely related to the presence of a previous history of twins in the female’s immediate or collateral family. Twin pregnancies are mainly categorized into dizygotic and monozygotic twins. Dizygotic twins are twin pregnancies formed by the fertilization of two separate eggs, accounting for 70% of twin pregnancies, and are associated with maternal race, age, and genetics. Monozygotic twins are formed by the division of a single fertilized egg, so the fetuses of monozygotic twins have the same genetic material. It accounts for 30% of twin pregnancies, its formation is unknown, and it is independent of genetic or environmental influences. Therefore, men and women with a history of twins in their family have a higher chance of having twins. Relatively speaking, genetic factors predominate on the female side of the family. However, there is currently no genetic correlation as the use of ovulation stimulants by women in preparation for pregnancy also increases the chances of twin births. Since the risk of twin pregnancy is significantly higher than that of single pregnancy, women should consult an obstetrician and have regular prenatal checkups in regular hospitals to avoid the emergence of special conditions during pregnancy and to handle them as soon as possible after they are confirmed to be pregnant.