Human Growth and Development

Birth and Lactation

What is the difference between fraternal and identical twins?

Fraternal, or dizygotic twins, develop when a woman ovulates two separate oocytes that are fertilized by two different sperm. Fraternal twins do not resemble each other any more than other brothers and sisters of the same parents resemble each other. They may be of the same sex or different sexes.


This is a web preview of the "The Handy Anatomy Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App