In the wild many animals are often born a lot of babies at a time, but people in 250 births, one child has one case of birth of twins. Scientists distinguish between monozygotic and dz twins, but in spoken language they are called or of identical and fraternal twins and twins.
Identical twins develop from a single fertilised egg that divided into two or more parts, began to develop separately. Thus, all the embryos are given the same set of genes and develop about the same. Such children always have the same gender and very similar to each other, sometimes even parents can't tell them apart. Although sometimes they have a mirror features: for example, a mole on the right side, the other on the left, one right handed and the other left-handed. They have similar traits, almost the same temperament, predisposition to disease and sometimes even fate.
The births of monozygotic twins is several times more rare than fraternal, as for the normal pregnancy, the egg split into several parts unusual.
Fraternal twins have different genes, since their conception participated of different sperm and eggs. In some cases women for one menstrual cycle to Mature two or more eggs, if they are all fertilized, it will begin a multiple pregnancy, and the light will be two or more children. It is quite common are cases of some Nations, they are very common – it is believed that prolificacy has a genetic nature.
Genotypes have fraternal twins, which is also called the twins, are different, so children may be different sexes and generally differ from each other as ordinary brothers and sisters. It is known that with age the risk of multiple pregnancies in women increases.
Found another type of twins, which is called a transition between the described two – polar or polyidentities. This occurs when two different sperm fertilize the egg and formed with it the polar body (it usually dies). As a result, the obtained half-embryos a different set of genes from the same mother.
Identical twins
Identical twins develop from a single fertilised egg that divided into two or more parts, began to develop separately. Thus, all the embryos are given the same set of genes and develop about the same. Such children always have the same gender and very similar to each other, sometimes even parents can't tell them apart. Although sometimes they have a mirror features: for example, a mole on the right side, the other on the left, one right handed and the other left-handed. They have similar traits, almost the same temperament, predisposition to disease and sometimes even fate.
- Known cases of separated at birth identical twins that never knew each other, lived almost identical lives.
The births of monozygotic twins is several times more rare than fraternal, as for the normal pregnancy, the egg split into several parts unusual.
Fraternal twins
Fraternal twins have different genes, since their conception participated of different sperm and eggs. In some cases women for one menstrual cycle to Mature two or more eggs, if they are all fertilized, it will begin a multiple pregnancy, and the light will be two or more children. It is quite common are cases of some Nations, they are very common – it is believed that prolificacy has a genetic nature.
Genotypes have fraternal twins, which is also called the twins, are different, so children may be different sexes and generally differ from each other as ordinary brothers and sisters. It is known that with age the risk of multiple pregnancies in women increases.
In countries where it is accepted to give birth after the age of thirty, for example, in the United States or European countries, births are fraternal twins more.
Found another type of twins, which is called a transition between the described two – polar or polyidentities. This occurs when two different sperm fertilize the egg and formed with it the polar body (it usually dies). As a result, the obtained half-embryos a different set of genes from the same mother.
