What is the story of the twin baby!

We all read in class 11-12 that sperm can fertilize only one egg, so how do you have twins?

Before that, we don't know why one sperm fertilizes only one egg, why can't more than one sperm?Capacitation process has to be completed before the sperm can fertilize the egg.

Sperm are surrounded by a coating of glycoproteins and other plasma proteins.  If this coating is not removed, the sperm epithelium and the ovarian epithelium cannot merge.Capacitation is the process of removing this protein coating.This process is not completed on time in all sperm.

After the sperm and the ovarian wall merge, the ovarian wall (Jona pelucida) changes its structure and the ability to bind the sperm is lost.As a result, no other sperm can penetrate the wall.This is why only one sperm can penetrate the ovarian wall.

When twins are born, there are two eggs.  Two sperms merge with two eggs to form two embryos.They also have different placentas.

In another case, a sperm fertilizes an egg.  After 2-3 days of fertilization, the embryo is divided into two parts.Their placenta is but one.

The children in the first field are not Identical Twin, which means that there are many differences in their behaviour, appearance, temperament, but the children in the second field are Identical.  There are many similarities in their appearance and behaviour.We ourselves become confused as to who is which.