Â· 4 years ago. A mutation is a change in the genetic material of an organism. We are made from trillions of cells, each with a nucleus composed of DNA â a set of instructions that tells the cell what to do. Cells copy themselves with astonishing accuracy, but every now and then a piece of code is copied incorrectly.
Identical (or monozygotic) twins happen when a fertilized egg splits into two separate babies-usually within the first twelve days of Mom's pregnancy. After twelve days, the egg may not split entirely and result in conjoined twins.
Dizygotic twins (= fraternal) and Monozygotic twins (= identical). 1. Dizygotic Twins. It is generally happening when the ovaries release two eggs and both eggs are fertilized by sperm (2 in this case). they are each formed from a separate egg and a separate sperm. If both zygotes implant in the uterus, youâve got twins..