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.
A robinâs eggs hatch 12 to 14 days after they are laid. Robins lay three to five eggs during their first nesting season, one egg each day until the clutch is complete. Continue Reading. Robins keep the clutch cool before the last egg is laid so the nestlings all hatch at approximately the same time.