Twins by different genders, also known as dizygotic or fraternal twins, are two individuals conceived from separate eggs fertilized by two different sperm. These twins can be of different sexes.
Dizygotic twinning is relatively uncommon, occurring in about 1 in every 80 births. However, there are certain factors that can increase the chances of conceiving fraternal twins, such as advanced maternal age, certain fertility treatments, and a family history of twinning.