Occasionally two (or even more) eggs are released by the ovary and both fertilized. This results in fraternal twins. This used to be uncommon but the rate of fraternal twins and multiple pregnancies are on the increase due to fertility treatment becoming more popular. Such twins will be no more similar than any other siblings as they have been conceived from separate egg and sperm cells. They may even be of opposite sexes.
More rarely, an embryo splits into two and two new beings begin to develop. This instance will produce identical twins: siblings completely alike in their genetic material though still two distinct beings.
0 comments