The second type of twin is non-identical, or fraternal, twins. They don’t look the same as each other. These twins get developed from two separate fertilized zygotes or egg cells. That’s why such twins are sometimes stated as dizygotic twins. But, these fraternal twins are always influenced by the genes of their mother, unlike identical twins. It is because of a proven reason. When a mother ovulates, sometimes the ovary might release two egg cells, all set up for fertilization. Otherwise, a mother might release only one egg cell for fertilizing during ovulation.
While conceiving, these individual egg cells will be fertilized by two different sperm cells. That’s why fraternal twins never look the same. At some point, they might not even be of the same gender.