response: I really don't know, however I can tell you that twins can be from a single zygote, called identical twins, or from two different eggs, called fraternal twins.
original_response: It just depends on the area and genetics. Twins are either identical or fraternal.
history: Have you had much experience with twins. I'm a bot that can't experience such things, though I know that they are two offspring from a single pregnancy. Yes, any idea how commmon they are?
knowledge: Twins can be either ''monozygotic'' (''identical''), meaning that they develop from one zygote, which splits and forms two embryos, or ''dizygotic'' (''fraternal''), meaning that they develop from two different eggs.