Why are born twins
For women, the most physiologically bear a baby. But there are multiple pregnancies, in this case twins or triplets are born. This is not an uncommon phenomenon, for example, for every 40 births are twins one. To understand why the twins are born, you need to know, at least in general terms, how fertilization takes place.
About once a month, in the middle of the menstrual cycle in healthy women ovulate. Matured egg is ejected from the ovary into the abdominal cavity. There she is captured by the funnel of the fallopian tube, which meets with the sperm. After fertilization, the egg gets to the uterus where the embryo begins to develop. But sometimes two at the same time mature egg that can be fertilized. In this case, each embryo will develop independently within their membranes and is associated with the mother's own placenta. Such twins often do not even like each other, they can be of different sexes, they may have a different blood group. This is because each egg is quite unique. Such children are called fraternal twins. Identical twins are obtained by fertilization of one egg with a large nucleus and double or even triple set of chromosomes. Such abnormal egg called polyploid. Similarly, the male germ cells may also have a double set of chromosomes. These sperm cells are also called poliploidnymi.Kogda found polyploid polyploid sperm and egg, two embryo develops after fertilization. This kind of twins is much rarer. Identical twins are always the same sex. They have the same appearance, the same propensity to disease. This similarity extends to the properties of the mind, the characters have too often similar. Such twins feel for a soul mate, even from a distance. Often, and the fate of such people are the same. Many women dream to give birth to twins. Most often this happens if in the family there were cases of the pair of twins born. In vitro fertilization often develops multiple pregnancy. With age, the ability to conceive twins increases somewhat, especially if a woman has already had childbirth.