Biological characteristics of twins
The birth of twins is a process that is still under-explored by modern medicine. Currently known 3 version of multiple pregnancy, after which twins are born.
The first option is the egg after fertilization, one sperm begins to divide by 2, 3 or more parts. In the future, babies born called monozygotic or identical twins. Such a pregnancy can develop in different ways: total fetuses, the fetal bladder and the uterus, each fetus has its own amnion, but they have a common placenta, each of your fetus, the placenta and the bladder.
The second option – monozygotic (polyidentities) twins. This is a rare case. The emergence of such a pregnancy is quite complicated. The egg even before fertilization has a polar body, which must then wither away. If not, it may also develop pregnancy. Moreover, in this case the polar body and the egg can be fertilized or one or more spermatozoa.
As for dz twins, they are born if 2 eggs are fertilized by 2 sperm. The percentage of overlap of genes in this kind of twins is 50%. Each of these fruits has its own SAC and its own placenta.
Exterior features twins
Identical twins that have the same set of genes, very similar in appearance. However, with a mirror similarity is born, only a small percentage (approximately 25%) of these children. All identical twins have the same blood type, and most - even fingerprints. Identical twins are born only same-sex.
A curious feature of poledancing twins when their external similarity, they can have different gender. Dz twins, which is popularly known as twins as like each other as much as normal brothers or sisters. They can be same-sex and opposite-sex.
The differences between the twins from twins
Thus, it is possible to summarize that the difference between the twins from the fraternal twins is as follows:
From a medical point of view, the twins are children born in one pregnancy. That is, they are like twins and triplets.
Twins are different according to the type of fertilization: polyidentities, identical and dz. Polyidentities are externally identical twins, however, they may be different sexes; identical – externally similar and of the same sex; dz twins, appear different from each other.