In the US identical twins are less common than what are called fraternal twins or non-identical twins. Geneticists prefer to call identical twins monozygotic because they arise from one fertilized egg. This makes fraternal twins dizygotic because they are just separate siblings who happen to gestate together.
Twins are common enough to have inspired myths in every culture.
Since the chances of being a singleton are so overwhelming, people ages ago had to explain something rare. They came up with some strange ideas. One was the belief that the woman had intercourse with her husband and with a deity, resulting in a demi-god and a mortal. If the deity was appreciated or feared, that could be a great benefit to the twins who would be given special favors or respectful distance. These cultural traditions may have led to selection for or against twinning.