How do twins end up fraternal or identical?
Fraternal twins develop from two eggs that are released and fertilized at the same time. They’re known as dizygotic (DZ). Identical twins develop from one egg that splits into two and are thus known as monozygotic (MZ). By the way, since they come from the same egg, monozygotic twins do share the same DNA, but these so-called “identical” twins are never truly the same. Although they have the same genetic makeup, they may have distinguishing characteristics that allow their parents to tell them apart. This may be due to environmental influences, either inside or outside the womb. Also, certain genes may end up being expressed differently in each twin.
