#2: Fraternal twins can look very different
A brother and sister born on the same day may be twins, yet look no more alike than siblings born years apart. That is the simple surprise that fraternal twins can look very different. These twins come from two separate eggs fertilized by two separate sperm, so they usually share about half their DNA, just like ordinary brothers and sisters. One may have curly dark hair while the other has straight blond hair. One may be tall and narrow-faced, the other shorter and round-cheeked.
