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.
Fraternal twins happen when two eggs are simultaneously fertilized instead of just one. A fatherâs genes canât make a woman release two eggs. It sounds like fraternal twins do indeed run in your family! But, since your son is the father, his genes are on the wrong side of the family tree. So, your family history likely didnât play a role in his wifeâs twin pregnancy.