How does meiosis work with mixed twins?

Explanation: Fraternal twins occur when the female produces two eggs and identical twins occur when the female produces one egg and the zygote spontaneous divides into two. In this case, the zygote undergoes cleavage(cell division by mitosis) when embryo is at two-celled stage.
The two blastomeres may separate and then each behave as an independent zygote.
Thus each broken blastomere give rise to a new independent individual.
As both the organisms are produced as a result of mitosis, both have identical genetic makeup and are called identical twins.
These twins involve sort of asexual reproduction after the normal sexual reproduction.
Identical twins can't be of different genders. Mean both will be either males or females.

Hope this helps !!!