They claim that the "discovery" of two semi identical twin brothers, according to geneticist Vivienne Souter of the Banner Good Samaritan Medical Center in Phoenix (USA), they are between identical twins and twins.
This type of twins occurs rarely, but to a lesser extent it is discovered, since for this there must be a reason for investigation, as was the case of these brothers, that one of them was born hermaphrodite (had ovarian tissue and testicular), the other is a male.
Babies are identical by the mother, but only share half of the paternal genes. This case occurs with two sperm, each contributes its genes, and a single ovule.
Recall that identical twins are the fruit of an egg fertilized by a sperm and form a zygote that later divides into two, developing two fetuses. Depending on the time of division, that is, if it occurs between the first and fourth day after fertilization, each fetus would have its placenta and its own amniotic bag, but if the division occurs between the fourth and eighth day (75% of cases), each fetus will have its own bag but will share the placenta. The pregnancy of twins is produced by the fertilization of two ovules and two sperm cells, resulting in two different embryos that coincide in time, each fetus has its amniotic sac and its placenta and may be of the same sex or not.
The semi identical twins were conceived naturally and were born normally, nor have they found abnormal growth or mental abilities.
According to the digital journal Nature, where the research has been published, only 1% of pregnancies occur as double fertilization, when two sperm fertilize an egg, and these embryos rarely survive.
