#9: Fraternal twins come from two eggs
Here is the companion piece to the identical-twin story. Fraternal twins come from two eggs, each fertilized by a different sperm during the same pregnancy. The formal word is dizygotic, but the family version is easier to picture: two siblings sharing the same womb at the same time. They can be two boys, two girls, or one of each. They may look alike, or they may make strangers doubt they are related at all.
