Why are there twins but they don't look alike? Maybe a question like this has crossed your mind. In fact, not all pairs of twins have the same face, aka identical twins. How come? This is why there are identical and not identical twin pairs. According to medical science, identical twins or not based on the number of eggs and sperm cells that play a role in fertilization and how they grow in the mother's womb. Identical twins Identical twins occur when a sperm cell fertilizes an egg. The fertilized egg then splits into two. The result is an identical twin fetus with the same gene or DNA, because it comes from one egg and one sperm cell. Therefore, identical pairs of twins always have the same sex (women or men), their faces look very similar, and usually share the same placenta in the womb. Unidentified Twins (Fraternal Twins) Did you know that identical twins are more common than identical twins. About 2/3 of the cases of twins are not identical twins. This twin occurs