Identical (Monozygotic) Twins

How: Identical twins form when a fertilized egg splits into two babies. This event usually occurs within  the first twelve days. Some people actually believe that if the egg splits later in the pregnancy, the more likely the twins will have similar features since they had additional time to lay "identical" genetic groundwork.
Why: As far as scientists can determine, there is no specific reason of why the egg splits. It is just a natural random occurence. 
    Identical twins have almost identical brain wave patterns. they can also sharesimilar characteristics. Identical twins actually share the same DNA but do not have identical DNA. When the egg splits, the DNA is not split in half perfectly, therefore, it is similar but not identical.
*You can actually have identical twins but twins are opposite genders. Most identical twins are the same gender though.
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