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Why Identical Twins Are Born?

Babies are beautiful. These bundles of joy enlighten the life of their parents. Twins are equally mysterious. Twins are still an unusual incident.  Only 3 cases include twins if there are 100 cases of birth. But what is the cause that some parents have twins? Here is a detailed discussion.

Types of twins

 There are two types of twins.

  • Monozygotic twins of identical twins(Look identical)
  • Dizygotic twins or fraternal twins9look different)

Monozygotic Twins

 Monozygotic or identical twins are born from only one egg. After fertilization, the egg gets implanted in the uterus. In some cases, the egg becomes divided into two different parts before the 12th day after conception.  The zygote is now divided into two halves and each half develop into babies.  These twins are called identical twins children.  They look alike and in most cases are of same-gender i.e, both are female or male.


 Research is still going on to determine the factors which cause the birth of identical twins. But doctors have proposed some theories about the factors which are-

  • Age of the egg
  • A certain enzyme present in the sperm
  • Mutation in the cells of the blastocyst

Identical twins are still treated as magical. In many cases, identical sisters marry identical twins.

Dizygotic or Fraternal twins

Dizygotic twins form when two or more eggs are released during ovulation and all of the eggs get fertilized. Dizygotic twins can be triplets (three babies), quadrangulates (four babies) and more. But there is still no human cases of dizygotic cases other than triplets.  These twins do not look alike and are also called fraternal twins. They can be both female or male or a combination of both.


Dizygotic twins are the direct cause of hyper ovulation of excessive ovulation. But the exact factor that triggers hyper ovulation is still not known. Some factors of Hyper ovulation are-

  • If birth control pills are used irregularly or they are stopped hyper ovulation may occur.
  • Breastfeeding
  • Obese women have more chances of getting hyper ovulation
  • Fertility drugs like Clomid may trigger hyper ovulation
  • Often some woman carries a gene responsible for hyper ovulation. This gene causes fraternal twins to be born. Both male and women carry this gene but in men, it remains inactive. Usually, the father passes this gene to their daughter while mothers pass it to their sons.
  • Family history is very much important. If a family has histories of twins then there are high chances of twins to be born
  • Older mother has more chances of hyper ovulation. After the age of 30, it becomes more and more common.
  • Particular races like Africans have higher chances of twin births.
  • Often yams contain phytoestrogen, plant counterpart of estrogen found in the female body. If these yams are a part of regular diet in a certain race or country, then the chances of hyper ovulation and birth of fraternal twins increase.

Hence, it is clear that some traits and genetic materials cause the birth of twins. It can be dizygotic twins or monozygotic twins. Certain races have higher chances of twins. While the older mother may give birth to twins in many cases. Whatever the cause be, the twins are still an enigma and magical.