"High orders of multiple births (three or more offspring in one birth) may result in a combination of fraternal (genetically different) and identical (genetically identical) siblings. The latter are also called super twins. For example, a set of quadruplets may consist of two sets of identical twins; in such a case each child has one identical and two fraternal siblings.

Identical triplets or quadruplets are very rare and result when the original fertilized egg splits and then one of the resultant cells splits again (for triplets) or, even more rarely, a further split occurs (for quadruplets). Alternatively the original fertilized egg can split twice (to produce four embryos) and all four may survive, to produce identical quadruplets, or one of the embryos may not survive and result in  triplets."                                                                                   - wikipedia

              

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Mother of Super Twins (MOST)

History of Higher Order Multiples

Higher Order Multiples Story

The Triplet Connection

Parenting Higher Order Multiples