Top Different Types of Twins
The world is full of all the miracles and extraordinary things,and these extraordinary miracles is what makes the world complete. Let us look at these miracles, in the context of a birth of a newborn. There are different kinds of babies that are born today- Twins, triplets, quadruplets, conjoined, parasitic, semi-identical, etc. A twin is one or two baby or an offspring produced in the same pregnancy.
Multiple births are basically rare in humans and can arise in different combinations, and it can vary from race to the genetic background. Twinning not only means looking alike, there a many forms of twins with different ages, gender, race, etc. According to the studies, these variations are caused by different racial groups or social class rather than hormone differences.
The odds of having multiple twins is almost 3 in 1,000 and their birth rates is about 32.2 in 1,000 and the identical twinning is not usually influenced by fertility upgrading treatments like drugs or in vitro. Here is the top ten list of twin birth rarities.
1. Conjoined Twins
Conjoined Twins are identical twins which do not separate fully from each other due to incomplete division of the ovum,and their bodies are joined together at birth. Almost have are stillborn and some pairs have abnormalities and this condition is mostly found among females. These twins will be connected at certain points of body and share a common tissue, organ, chorion, placenta, amniotic sac or limbs. The origin of conjoined twins is explained with two theories – fission and fusion.
In the fission, the fertilized egg splits partially and in fusion, the egg fully separates but the stem cells fuse the twins together. ‘Chang and Eng Bunker’ is the most famous pair of conjoined twins and due to rarity of this condition, ‘Siamese Twins’ is used as the synonym for conjoined twins. One more important fact about these twins, that is studied is that they cannot be of different genders. These twins are either two girls or two boys. This conjoined condition occurs 1 in 50,000 human pregnancies.
2. Half Identical Twins
Half identical twins or semi identical twins are a very rare formation of twinning in which twins inherit same genes from mother but different genes from father. These twins are half identical, they are not 100% match DNA but these twins are very much alike.
They can be of two types- Monozygotic(identical) which means they develop from two zygote and then split into two embryos or Dizygotic(fraternal) which means they develop from two eggs, inseminated by separate sperm cell. A single fetus is known as ‘singleton’ and and offspring of multiple birth is ‘multiple’.
3. Monozygotic Twins
Monozygotic twins means mono(single) zygote(fertilized egg). Monozygotic twins are formed with one egg and one sperm forms a zygote and then splits into two embryos. These embryos then forms separate fetus. These are also called identical twins because they share identical genes, but they are not perfectly identical, although can be very alike. These twins have identical DNA and the differences and variations are caused by environmental factors.
It means that the monozygotic twins are of the same sex, same physical traits and even almost similar personalities. Monozygotic twins also share the same placenta but have separate amniotic sacs. These twins are also called ‘maternal’ twins. This twinning occur at the rate of about 3 in every 1000 human deliveries worldwide.
4. Dizygotic Twins
Dizygotic means Di(two) zygote(fertilized egg). these twins are formed when two eggs are fused and fertilized by two separate sperms producing two separate zygotes. Usually women only release one egg in an ovulation cycle but sometimes multiple eggs are released leading to dizygotic twins. Dizygotic twins do not share same genes.
They occur when two or more eggs are released in one cycle and if both of them are fertilized, they result in dizygotic twins. They have very slight chances of having the same chromosome profile. They can be of the same sex or different sex too. These twins have their own placentas and amniotic sacs, and this is also known as being ‘dichorionic-diamniotic (Di-Di)’. If the Di-Di is low, they have the lowest mortality rate of all twins. These are also called as ‘non-identical’ twins or ‘fraternal’ twins.
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