Difference Between Fraternal and Identical Twins (With Table)

Twins are multiple gestations that are either Fraternal or Identical. Fraternal and Identical are two kinds of twins which differ due to fertilized eggs during the pregnancy. 

Fraternal twins are kinds of twins which have two eggs fertilized during the same time, which results in pregnancy. These kinds of twins, since developed from two different eggs, have their different amniotic sac.

Identical twins are different from Fraternal twins because, in this case, only one egg is fertilized but is divided into two embryos and further into two babies. These kinds of twins, since they developed from one egg, may or may not have the same amniotic sac.

 Fraternal vs Identical Twins

The difference between Fraternal and Identical Twins is that both may be known as twins, but Fraternal twins don’t usually have many similarities between them and are more like siblings, but Identical twins have astonishing similarities.

Fraternal Twins are born out of different eggs which don’t even share the same amniotic sac and don’t share the placenta as well. All this leads to maximum differences between the babies. These kinds of twins don’t have the same DNA and can develop at a different rate during pregnancy. 

Identical twins are born out of one egg which may share the amniotic sac and also may share the placenta. All this makes the twins very much similar. These kinds of twins have the same DNA and usually develops at the same rate during pregnancy.

Comparison Table Between Fraternal and Identical Twins

Parameters of Comparison Fraternal TwinsIdentical Twins
DNA Different Same
Health As develops in two different sacs there may be health issues in this kind Health: As develops in two different sacs there may be health issues in this kind / Growth rate is same which makes twins equal in health
Scientific term Dizygotic Monozygotic
LookJust like every other siblings this kind of twins look differentThis kinds of twins may or may not look alike
SexMay or may not be same-sex twins Same-sex twins
Blood typeMay or may not have same blood type Same blood type

What are Fraternal Twins?

Fraternal twins are dizygotic twins, which means that they are the results of fertilization of two different eggs at the same time, which results in pregnancy with twins. These kinds of twins do not share the same DNA. 

Fraternal twins don’t look the same and don’t have the same blood group as well. These twins as formed from the different amniotic sac. This kind of dizygotic twin has a different placenta. The formation of an embryo is by two different eggs and sperms, which makes both the embryos only 50% alike. 

These kinds of twins are more like siblings. Just like any other siblings, these twins also may or may not have the same blood group or have similar characteristics. Half of the genes of these twins match just like siblings. In this kind of twins, it is more likely of them to be connected but distinctive.

When the sex of twins in the womb is of different sex, it is always Fraternal Twin as a different-sex twin is not possible in case of Identical twins due to the difference in the DNA. Same-sex twins can also be Fraternal twins, but different-sex twins are fraternal twins.

What are Identical Twins?

Identical twins are monozygotic twins, which means that they are results of fertilization of one egg and one sperm which during the development of the embryo splits into two half. The embryo, during the development of the cell its splits into two half and later turn into two individuals.

Identical twins share the same DNA, which also leads to the same sex. As one egg and sperm after fertilization form, an embryo that has one particular sex divides into two half. Both the half have same DNA and Sex as well. The sex difference will mean different DNA as a boy have an XY chromosome, and a girl has a XX chromosome. 

Identical twins literary though means identical by look may not always be that case. The facial structure of a person always varies depending on the circumstances and other factors. The twins, due to some different circumstances in the outer world or womb, may become different in the case of facial structure.

It is according to some researches that one in every three sets of twins are Identical twins and approximately one-quarter of identical twins are a mirror image of each other. As Identical twins are most likely in the same amniotic sac, their development is very likely the same, which makes the pregnancy a little bit more safe for both babies in case of health issues.

Main Differences Between Fraternal and Identical Twins

  1. Fraternal twins don’t have the same DNA. On the other hand, Identical twins have the same DNA, which makes them very similar in traits. 
  2. The body or facial structure may or may not be the same for Identical twins, but for Fraternal twins, it is surely different and is just like siblings.
  3. The Fraternal twins may or may not be of same-sex. On the other hand, for Identical twins, it is precise of same-sex.
  4. In the case of Fraternal twins, two zygotes are formed with two eggs and two sperm. On the other hand, in the case of Identical twins, one zygote is formed with one egg and one sperm and is divided into two, and further develops into two embryos.
  5. Fraternal twins always develop in different amniotic sac with different placenta. On the other hand, Identical twins may or may not grow in one amniotic sac with one or two placentae.
  6. The health or physicality of both the babies can vary in the case of Fraternal twins, but for Identical twins, it’s usually the same as the process of their development is similar.


Every pregnancy has its procedures, while in the case of twins, there is always a risk because of the complications of two babies in one womb. But all these complications are very small now with new technologies and experiences. For many ages, twins are given birth without any problems.

Though Fraternal twins or Identical twins are born together or may have the same DNA or look alike, each of them is individual first. Each person faces different situations and circumstances, which makes them unique in themselves.


  1. https://www.cell.com/molecular-therapy-family/molecular-therapy/fulltext/S1525-0016(16)30416-6
  2. https://www.cell.com/molecular-therapy-family/molecular-therapy/fulltext/S1525-0016(16)30416-6
  3. https://www.tandfonline.com/doi/abs/10.1080/00223980.1990.10543255
  4. https://psycnet.apa.org/record/1937-04406-000
2D vs 3D