Which is the largest twin brother?

What is it? The first born? Does the first in shape?
Much has been said about that first birth is the lowest and the highest last. None of that is true. For the law, the first born, is undoubtedly the largest. Simple question of logic. In biology, everything is possible.

In the case of identical twins, generated from a single fertilized egg, both biologically-be-equal in age, and that his life began simultaneously.

If these are simple twins, the product of fertilization of two different eggs by two different sperm, there is-to-date any possibility of knowing if the fertilization was simultaneous or deferred.

And in the case of in vitro fertilization?
Even if, as in the case particularísimo of in vitro fertilization, we know exactly the time at which each egg was inseminated and the time at which each embryo was transferred to the interior of the uterus, we will never know which is which at the time of birth. That figure could only be made known whether a biopsy for genetic study of the embryo before transferring to the uterus, something-for now-is only possible in very limited. Most countries where technically feasible, the laws are very strict regarding the possibility of the so-called "pre-implantational biopsy of embryos.

Almost science fiction. Hence, not to discuss more: the first birth is the largest, but in reality was the ultimate gesture.

The enigma of twins

The behavior of the four Genain twin sisters, born in the U.S. in 1930, drew the attention of psychiatrists at the time.
As a child, Hester broke light bulbs and was booted ios buttons; Nora gems during meals and put on their knees and elbows to bleed, with 22 years, Iris stopped working because he felt "trapped"; Myra was better, but are easily frightened and reassure her hard work.

The four were diagnosed with schizophrenia, which seemed to prove the importance of genetic factors, since the probability that the disorder affects four people chosen at random is 1 in 100 million.

Moreover, the degree of gravity was different in each one, which indicated the presence of other factors, but what?

The psychologist David Ro-senthal explained the differences in degree from family relationships, as Myra, the less sick, was the favorite of the mother, and Hester, the most serious, since girl was labeled as "bad".

For his part, the neuropsychologist Alian F. Mirsky discovered that the twins through tomography most affected also showed more abnormalities in their brain activity and that their frontal lobes, which act as a focal point for information, were weaker and less energy consuming than those of their sisters.

According Mirsky, Genain suffered varying degrees of injuries due to the order of their birth. Nora could suffer trauma as the first to pass through the uterus and Hester, most recently, by lack of oxygen.

The brain scanner in a recent case of twins, Elmore, proved that the ventricles of Steven, schizophrenic, had thicker tissue and neuro-nal thinner than the mentally healthy David.