Fraternal twins, also known as dizygotic twins, occur when two separate eggs are fertilized by two separate sperm. This results in two babies who are not identical and who do not come from the same egg. Fraternal twins can consist of two girls, two boys or one girl and one boy.
Fraternal twins are only as genetically similar as any set of siblings. Since they do not come from one egg as identical twins do, they have completely different DNA. Identical twins, or monozygotic twins, come from the splitting of one egg fertilized by one sperm cell. Because of this, identical twins share the same DNA.