MZT is an acronym used for monozygotic twins.  From the term itself, MZT or monozygotic twins come from one zygote or fertilized egg. This is in contrast to the other type of twins called dizygotic twins which come from two different fertilized eggs.  For most people, when talking about the subject of twins, they would always refer to the monozygotic type because of similar physical appearance. MZT or monozygotic twins are also referred to as identical twins because of many similarities.  On the other hand, dizygotic twins are also called non-identical twins.

Monozygotic twins are babies that are formed from a single fertilized egg.  This is the main reason that many DNA and cells are similar or identical.  This also explains why twins that come from one zygote basically look the same.  Sometimes people may even have a hard time distinguishing one from the other when it comes to MZT or identical twins.  In terms of DNA though, not all are actually identical. The more appropriate term for DNA and other cells of monozygotic twins is “similar”. There are various DNA that basically resemble each other and there are some parts that are slightly different.  With slight differences in some cells, MZT or identical twins will also have slight differences in their appearance, behavior, and even their chances of getting a particular illness.  Some twins may not have the exact shade of brown hair, while others may also differ in terms of social behavior.  There are also identical twins that differ in terms of organ and immune system development and this explains why one child is more prone to have respiratory illness while the twin brother or sister is more likely to get stomach ailments.

MZT or monozygotic twins account for about 1/3 of all twin births in the world.  This means that more twins are actually born from two different zygotes rather than one.  Studies have also shown that heredity does not play a factor in terms of producing MZT or identical twins.  Many experts have also pointed out that producing identical twins or MZT does not necessarily result from various fertility treatments.