How are twins really born?

fraternal- 2 different eggs fertizaled during the same cycle. They actually have no more genetic material similar than normal siblings. They just happen to be born at the same time. This type of twin can be genetic, altnough only thru the maternal line. Its because the woman has a gene that may make her produce more than one egg during her cycle. Identical- 1 egg that was fertilized by 1 sperm. the egg then splits, so the twins have the exact same genes. This type of twinning is not genetic. Theres also a type of twin that is from 1 egg that has already split and so then they have 2 differnt sperms fertilize the split egg. These twins have 75% of the same genetic material... Most of these types of twins are just assumed to be idential.