What Distinguishes Twins from Doublets 0 16

Do you remember the old episode of “Yeralash,” where the brothers tried to explain to a passerby that they were not twins? “But you are brothers? Brothers. Birthday on the same day? On the same day. So, you are twins.” In fact, there is a fundamental difference between twins and doublets.

So, what is the main difference? In medical terminology, the concepts of monozygotic and dizygotic twins are used. Twins are two or more children who grew together in the mother's womb and were born almost simultaneously. Dizygotic twins are referred to as doublets, while monozygotic twins are simply called twins.

Here’s what distinguishes them:

* Doublets can be of the same sex or different sexes. However, twins are always of the same sex.

* Twins are always identical. They are difficult to distinguish externally, especially for outsiders. They have the same blood type, identical diseases, and complete facial resemblance. Doublets look like siblings, as if they were born to the same mother, but at different times.

* Twins are born approximately once in 4,000 births. Doublets are a more common occurrence, once in 1,000 births.

* To conceive twins, only one egg is needed, while doublets require 2 different eggs.

* When conceived in vitro, the chance of having doublets increases. The likelihood of having twins is also higher for women who have been taking hormonal contraceptives for a long time before conception.

Twins come from one egg, which requires only one sperm for fertilization. Then, for reasons unknown to science, it splits into two parts. As a result, genetic copies are formed. Each of the cells will develop into an independent embryo.

A visible distinguishing feature of already born babies is their “similarity” to each other. Twins always look alike, while doublets do not. From a medical point of view, things are a bit more complicated. In medicine, there is no concept of “doublets” and “twins”; there are concepts of monochorionic and dichorionic twins. The difference lies in how fertilization occurs.

Dichorionic twins are characterized by each embryo forming its own placenta and amniotic sac; therefore, each baby has its own space in the womb and feeds from its own placenta. From a medical standpoint, this is more favorable for the birth of healthy babies.

In monochorionic twins, both embryos develop in one embryonic sac and always share a common placenta, which, in some cases, complicates the course of pregnancy and leads to a number of complications.

Children from monochorionic twins are often genetically identical, of the same sex, and very similar to each other, and they are called twins. As for dichorionic twins, the babies can be either of the same sex or different sexes and do not resemble each other at all.

Doublets, on the other hand, develop from two eggs fertilized by sperm. They can even have different fathers. This occurs because, in rare cases, two eggs are released from a woman's ovary during ovulation, although usually only one is released. For this reason, fraternal twins or doublets are born in the family.

So, twins are natural clones with identical appearance, character, and even hereditary diseases. They cannot be of different sexes. Doublets are brothers or sisters or a brother and sister who have similarities and differences, as if they were born not simultaneously, but as a result of different pregnancies from the same mother.

Researchers at the University of Washington conducted a series of studies regarding the lifespan of monozygotic twins. It turned out that male twins live six percent longer than their peers, while females outlive them by a full ten percent.

Interestingly, other studies also concerned the mothers of twins. Biologists from the University of Utah found that women who gave birth to twins have a lifespan that is nearly eight percent higher than those who gave birth to one or several children with intervals.