Twins are one of the most delightful creations of God. Being blessed with two babies at once is a miracle not every woman is capable of achieving. However, the possibility of conceiving twins is not as easy as it seems.
Age, heredity and various other physiological factors affect the mother’s ability to deliver twins. Interestingly, the African continent records the highest rate of fraternal twin births. The Asians on the other hand have the lowest incidences of fraternal twins. The European countries record higher rate of fraternal twin births when compared to Asian countries but are lower when compared to African countries.
Listed below are some interesting facts about fraternal twins:
Formation of Fraternal Twins:
Fraternal twins are formed from a pair of eggs and sperms. This could occur if the mother’s ovary releases two eggs at once as opposed to the normal cycle of one egg per menstrual cycle. When two eggs are released, the chances of two sperms surviving and fusing with two different eggs are very high. This leads to development and formation of two different zygotes, developing with two different placentas. Therefore, fraternal twins are independent of each other’s development. Identical twins on the other hand are formed from fusion of a single egg and sperm. This zygote divides after a certain stage and forms two different embryos.
Sexual Development of Fraternal Twins:
While identical twins can either be boys or girls only, fraternal twins can be:
iii)A boy and a girl
This occurs because identical twins are formed when a single embryo fused from a single sperm and egg divides. This makes the sex of the two babies identical when they split because they carry the same set of genes. Fraternal twins on the other hand are born from fusion of two separate sperms and eggs, making it possible for the chromosomes to fuse differently, leading to differences in combination of the X and Y chromosomes, giving greater chances of mixed combinations. This could lead to fusion of two XX chromosomes (girl babies) or two XY chromosomes (boy babies) or one XX and one XY, leading to formation of a girl and boy respectively.
Chances of Conceiving Fraternal Twins:
Nearly 60 to 70 percent of twins born the world over are fraternal in nature. Only a small percentage of twins are identical. If you have already delivered a pair of fraternal twins, you have higher chances of giving birth to fraternal twins again. The chances of having fraternal twins increases with age but is also considered to be hereditary in nature. Identical twins on the other hand are formed due to abnormal development of the embryo during its divisional stages, leading to complete division of an embryo into two different pieces, giving rise to two babies. This makes identical twins deliveries a case of probability and is not hereditary in nature.
Fraternal Twins can Look Alike:
Fraternal twins share exactly 50 percent of their genetic make up with each other. This means, all fraternal twins need not necessarily look strikingly different from the other. In fact, in some cases, fraternal twins can look amazingly similar, making many to believe that they are absolutely identical rather than fraternal. Therefore, in some cases, you might have to go in for DNA testing to prove whether the twins are identical or fraternal.
Irrespective of the nature of development, twins are known to respond, behave and develop differently, not making them any different from normal siblings.