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.
The answer to this question depends on what type of twins they are! There are two types of twins. In one case, twins can be produced when two eggs are present at the same time inside the mother, and both of these eggs get fertilized. Each of them eventually grows into a separate baby. Because each egg and each sperm started with different DNA, the babies that grow from each have different DNA.