Brother twins share 100 DNA

Gemini univitelinos definition, types and properties

The TwinsUnivitans are those that come from the same zygote, this is how two babies are formed with the same DNA.

These types of brothers are always of the same sex and blood type. The division of the egg determines whether the twins share the same placenta.

There are several types of twins: the bicigóticos and the monozygotes. Clustering within these monocorial and bicorial

Factors of having twins univitelinos

First, the term twin primarily refers to two individuals or one of two individuals who share the same uterus and are usually born on the same day. That is, they are two children from the same pregnancy.

These twins may also be monozygous or also known as identical twins or bicigóticos, although they are also known as dizygoti twins.

In the case of identical or univitelline twins, embryos develop from a zygote, which divides to produce two embryos. And in the case of bicigóticos, they develop from different ovules.

In this latter type, each twin is fertilized by its own sperm cell and has its own placenta and amniotic sac.

As a curiosity, bicyclic or bivitelline twins, like any other sibling, have a very small chance of having the exact same chromosome profile. These type of twins can be of the opposite sex or the same sex, and like all siblings, they share 50% of their DNA.

Two thirds of all twin births result in dizygoti twins of the same sex and one third are dizygoti twins of different sexes. About two-thirds of all births to this type of child are fraternal.

Univitelline or identical twins

Univitelline twins are those who come from the same zygote, this happens when a single egg fertilized by a sperm is divided into two identical halves, that is, two separate babies are formed, but with the same DNA.

These type of twins are always of the same sex and blood type and almost always share the same placenta, but sometimes they can have separate placentas. It is the parts of the ovule that determine whether or not identical siblings share the same placenta.

In this type of pregnancy, the division usually occurs within the first few days. If the embryo is divided within two to three days of fertilization, the twins are bicorionic and diaminotic, which means that each embryo grows in its own amniotic fluid and feeds on its own placenta.

But if the embryo is split between 3-8 days, then they are monochorionic twins and biamnióticos divides the placenta, but grows in its amniotic sac.

Finally, if the embryo is divided between 8-13 days, then the twins are monochorionic and monoamniotic. However, the latter are the rarest because they divide both the placenta and the amniotic pouch, with the embryo being the only one to divide.

Within this group we can include the Siamese twins, the division of which the zygote takes place after day 13, is incomplete and is connected by part of the body.

Twin or bicyclic twins

On the other hand, pregnancies of dizygotic, bicyclic, or bivitelline twins usually occur when two fertilized ovules are implanted in the uterine wall at the same time.

But when this happens, the process is done independently as two different sperm cells are fertilized, resulting in two dizygoti twins.

Fraternal twins are essentially two common siblings born at the same time, as they arise from two separate eggs fertilized by two independent sperm, in the same way as normal siblings. By and large, this is considered to be the most common type of twins.

Fraternal twins have an extremely low chance of having the same chromosomal profile as any other sibling, and even if they did, they would always have the same different genetic material on each chromosome because of their crossover during the meiosis process.

Dizygoti or dizygoti twins may look similar, especially considering they are the same age. However, they can also look very different.

The pregnancies of fraternal twins are more likely that the woman will meet some of these characteristics:

She uses fertility drugs, she is over 40 years old, the woman is of West African descent, she is older than the average height and weight, she has had several previous pregnancies, she is a bicigot twin. She has a family history of bicigotic twins, infertility treatments increase the number of dizygotic twins and approximately 35% of in vitro fertilization pregnancies.

Ethnic groups

About 1 in 90 human births is the result of a twin pregnancy.

Dizygotic twins or sibling rate varies widely between ethnic groups, extending approximately 4.5% for the African Yoruba ethnic group and 10% for Linha Sao Pedro, a small settlement in Brazil belonging to the city of Cândido Godoi; there, one in five pregnancies results in twins.

The renowned Argentine historian, Jorge Camarasa, put forward a theory about the attempts by Josef Mengele Nazi doctor who could be responsible for the high proportion of twins in the area. His research was rejected by some Brazilian scientists who had studied twins who lived in this region.

There was also a high rate of twin pregnancies in other parts of the world such as Igbo Ora in Nigeria, as well as Kodinji and Mohammadpur in India.

A study of the mother records 5750 women who lived in Nigeria in the Savannah area, 40 twins and 2 triplets were per 1000 births found 26% of them were identical.

The incidence of multiple births was about five times greater than that observed in any western population, was significantly lower than that of the other ethnic groups living in the hot and humid climates of southern Lebanon.

This incidence was related to the age of the mother and was not related to the climate or the prevalence of malaria.

On the other hand, the use of fertility drugs causes what is known as hyperovulation, which is nothing more than the stimulated release of multiple ovules by the woman.

This has caused what some call a Multiple birth epidemic. In 2001, the twin birth rate for the first time in the United States exceeded 3% of all births. However, the rate of identical or univitelline twins remains at 1 in 333 worldwide.

Behavior and environmental influences

Identical twins can behave differently than any other sibling because they develop their own personality so that they can be identified as individuals.

Many identical twins spend most of their time together, especially when they are children, so people often assume that they will act the same way.

However, this is not the case. Geminis are unique individuals who establish their own individual likes and dislikes, and there are usually obvious signs of difference when observed together or separately.

In contrast, univitelline twins have identical DNA, although they have different environmental influences throughout their lives. Which leads to the fact that the genes that can be activated or deactivated are affected. This phenomenon is known as epigenetic demodification.

Since the data, a study of 80 pairs of twins between the ages of 3 and 74 showed that the youngest twins have relatively few epigenetic differences, it means that the number of differences between identical twins increases with age.

According to the observation, the 50-year-old twins had more than three times the epigenetic difference of the younger twins. However, it also found that the twins, who had lived their lives apart from causes such as adoption from two different families of parents, made the biggest difference.

Study of twins

Twin studies are those that show the importance of ecological and genetic influences on phenotypes, disorders and traits; This is considered a key tool in behavioral genetics and in the content fields of biology and psychology.

These studies were used to track traits ranging from personal behavior to the presence of mental problems such as schizophrenia.

On a practical level, twins are a valuable source of observation as they enable the study of environmental influences and variable genetic makeup.

Identical or identical twins share almost 100% of their genes, this means that most of the differences between them, such as intelligence, depression, or susceptibility to boredom, are based on experiences one has but not the other.

In contrast, fraternal or bivitelline twins only share 50% of their genes in the same way as a normal brother, so they share many aspects of their environment, such as the type of upbringing, education, wealth, and culture, because they were born inside are from the same family.

The presence of a genetic trait in only one member of a pair of identical twins offers a window into the study of environmental effects. This is known as discordance.

In this way, the twins are also useful for demonstrating the importance of the unique environment specific to one or the other twin by studying the presentation of traits.

Changes in the particular environment may result from an event or incidence that affects only one twin, which may differ from a head injury or birth defect presented by one twin while the other remains healthy.

The classic twin design compares the similarity of identical twins and dizygoti twins. If identical or univitelline twins are significantly more similar than fraternal or bivitelline twins, it would mean that genes play an important role in these traits.

By comparing hundreds of families with twins, researchers can learn more about the functions of genetic effects such as the common environment and the unique environment in the behavioral configuration.

Modern twin studies have shown that almost all traits are partially influenced by genetic differences, with some traits having a stronger influence, e.g. B. Height, personality traits and some more complex inheritances.

Another finding from the study is that different genes affect different aspects of the trait, as in the case of autism.

Multiple pregnancies

For reasons not yet known, while the woman is older, it is more likely that she will have a multiple birth naturally.

With that in mind, there are hypotheses that suggest this is due to the highest level of follicle-stimulating hormone that older women possess.

Sometimes multiple pregnancies can involve more than two fetuses. When there are three, they are called the group of children, they are called triplets. If there are four quads, if there are five, they are called quintuplets, and so on.

Before the arrival of drugs to stimulate ovulation, triplet pregnancies were very rare, about 1 in 8,000 births. The births of more quantities were almost so strange that they were little known.

The average duration of pregnancy is about 37 weeks for twins, 34 weeks for triplets and 32 weeks for quadruplets.

There is currently no way to prevent twins from being born prematurely. In women with single fetal pregnancies, drugs called betamimetics can relax the muscles of the uterus and delay labor.

On this line, the administration of this drug could give more time to provide steroids for baby lung development or to transfer the mother to a hospital with a special care unit.


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