Two Latin words lead us to the concept of twin: gemellicius, which comes from gemellus (“twin”). They are twins those born from the same birth in species that are not characterize by multiple births (like the human species). In the case of animals such as cats or dogs, the term is not used.
Twins, therefore, are the people resulting from a single gestation and that, therefore, they share the uterus in a same pregnancy. This means that multiple pregnancies are usually completed in a shorter time than usual, since the space for the growth of twins is limited.
The notions of twin and twin they often cause confusion. In some countries, both terms are used synonymously, while in others, a distinction is made between twin (biviteline twins) and twin (univiteline twin).
This distinction indicates that twins are individuals originating from different ovules (with dizygotic pregnancy or polygygotic), while twins originate from the same Ovum (monozygotic pregnancy).
Twins or dizygotic twins, therefore, originate from the separate but almost simultaneous fertilization of two eggs by two sperm. These twins do not share a greater identity genetics than those siblings born from separate gestations.
Twins can be of different sexes, allowing twin pairs to be male-male, female-female, or male-female.
At the legal level, the older brother among the twins is considered to be the one who is born first (that is, the one who comes out of the womb first). In this way, said twin will be the firstborn and who will have the Rights corresponding according to the legislation. Despite this, it should be noted that the order of birth is not linked to the order of fertilization, but to the place of growth of each individual with respect to the exit of the uterus.
Twin and twin: differences and myths
As explained in previous paragraphs, the terms twin and twin are not always used clearly, and this leads to some confusion. On the other hand, myths have also been created regarding the relationships between siblings born from the same gestation, such as having a Connection psychic comparable to telepathy, which has not been scientifically proven.
Regarding the influence of genetic inheritance in the fact that twins or twins are born, it is correct to ensure that the first case has been proven by the medicine and it can be anticipated by studying the family history and certain physiological characteristics of the mother. Regarding the probabilities of having twins, there is no reliable evidence to determine them, although it is not ruled out that it will be possible in the future.
Many people believe that in twin pregnancy there is only one placenta and only one amniotic sac; however, this depends on the day the ovum divides, and the possibilities are diverse (one placenta and two amniotic sacs, two placentas and one amniotic sac, and so on). It is worth mentioning that if the embryo divides around day ten of gestation, then both organs will be shared.
One of the most widespread myths regarding the pregnancy of twins is that they do not feel the bond that is known as «link twin ». Various studies have proven that, since a person shares the beginning of their life with their twin brother in a very similar way to what happens with twins, they also experience a deep understanding on a psychological level.
To summarize the differences between twins and twins, we can say that
* the Twins: also known as identical twins; They share 1 egg and 1 sperm, which divides; they have the same gender; their physical similarity is very high, and they can become identical; they share all the genes.
* Twins: also known as fraternal twins; they are born from 2 eggs and 2 different sperm; they may or may not have the same gender; they can look as similar as two siblings of different gestations; they share half of the genes.