Difference Between Fraternal and Identical Twins

Fraternal vs Identical Twins
With the increased use of assisted reproductive techniques, the incidence of twins has increased in recent times. There are two type of twins a woman can have. These are fraternal twins and identical twins. While they share a lot of common features, they also have a lot of difference. Let us see how they are different:

Method of conceptions- fraternal twins are conceived of two different ova and sperms. Identical twins, on the other hand are conceived of the same egg and sperm which later divides into two. Fraternal twins have their separate set of placenta and sacs within which they grow. So, if your twins have separate sacs and placenta, they are usually fraternal twins. Identical twins on the other hand may or may not have separate sacs and placenta.

This often leads to confusion as to whether they are identical or fraternal. If the zygote (the fertilized egg) divides early enough, there will be two sacs, each with their own placentas. If they divide late, the two babies may share a sac and a placenta. This is considered complicated from a medical point of view. When twins share a sac, they are more prone to having problems with the cord etc.

Appearance-It is easier to tell the differences after the twins are born. Fraternal twins are about as alike as a brother and a sister. However, identical twins are usually very alike. In fact, if the parents are of mixed races, fraternal twins may resemble their father or their mother. So, with an African American father and a Caucasian mother, one kid may be afro American in appearance, while the other is Caucasian in looks!

Development-Development issues also indicate whether your babies are twins or not. Identical twins usually have very similar developmental patterns. In fact, you might see them speaking and walking with days of each other. Fraternal twins may have wide differences in these patterns.

While the difference fraternal and identical twins are important from a medical point of view, you should know that there is a scope for misdiagnosis also. For instance, even fraternal twins may have one sac if their separate sacs fuse into one before the ultrasound checks them out. On the other hand, with identical twins that have their separate sacs, it is very difficult to differentiate them from fraternal ones.
Once the kids are born, you can find out the differences between fraternal and identical twins by a non invasive DNA testing.

Summary:
1. Fraternal twins are composed of 2 separate eggs and sperms, while identical twins come from the same egg and sperm.
2. Fraternal twins vary in their appearance, while identical twins tend to look the same
3. Fraternal twins may grow at different rates, but identical twins will follow the same pattern of growth.

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