When sperm and egg unite, they create a zygote through fertilization. Over time, the zygote will divide into millions upon millions of cells. Each cell consists of 46 chromosomes; these cells, as a...
The frequency of having monozygotic twins (identcal) is about 4 out of every 1000 births. Whereas dizygotic twins (fraternal) is about 12 out of every 1000.