Dizygotic twins, also known as fraternal twins, occur when two separate eggs are fertilized by two different sperm cells during the same menstrual cycle. This results in two genetically unique siblings who share about 50% of their DNA, similar to regular siblings born at different times. Dizygotic twins can be of the same sex or different sexes, depending on the combination of the eggs and sperm involved. Factors such as family history, maternal age, and the use of fertility treatments can influence the likelihood of having dizygotic twins.