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.
Normally, a woman normally releases ONE egg per menstrual cycle. On occasion, a woman will release two, which would result in fraternal twins if both eggs are fertilized. woman's egg supply peaks before she herself is born, with at least 7 million eggs packed into the fetal ovary. By birth the number dwindles to a million, and then drops to 3 â¦ 00,000 by puberty, And not all matures.