About once a month, in the middle of the menstrual cycle in healthy women, ovulation occurs. The Mature oocyte is ejected from ovary into the abdominal cavity. There she is captured by the funnel of the fallopian tube, which meets with sperm. After fertilization, the egg enters the uterus, where it begins to develop the embryo. At the same time but sometimes two Mature eggs that can be fertilized. In this case, each embryo will develop inside of its amniotic SAC and is connected with the body of the mother's own placenta. Such twins often don't even like each other, they can be different sexes, they can have different blood type. This is because each egg is completely unique. These children are called daizepam twins. Identical twins happen when a fertilized one egg with large nucleus and double or even triple set of chromosomes. Such abnormal egg cells are called polyploid. Similarly, male germ cells may also have a double set of chromosomes. Such sperm also called polyploid.When there are polyploid polyploid sperm and the egg, which after fertilization develop two germ. This type of twins is much rarer. Identical twins always the same sex. They have the same appearance, a tendency to the same diseases. This similarity extends to the properties of the psyche, the characters are often too similar. Such twins can feel their soul mate even at a distance. Often the fate of such people is the same. Many women dream to give birth to twins. It happens more often if the family a couple were cases of multiple births. In-vitro fertilization is often a multiple pregnancy develops. With age the chance of conceiving twins increases slightly, especially if the woman was already in labor.