response: I'm not sure, but the Yoruba people have the highest rate of twins, and it's though to be a chemical in the yams that they eat.
original_response: Not sure. Perhaps fertility drugs. The Yoruba people have the highest rate of twinning, at 45-50 per 1,000 live births.
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? 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. How does a fraternal set of twins come about? For fraternal twins, each egg is fertilized by a different sperm cell. Cool, that's good to know. Any other interesting facts? The twin birth rate in the US has risen 76% from 1980 through 2009. I wonder why that would happen.
knowledge: The Yoruba peoples have the highest rate of twinning in the world, at 45–50 twin sets (or 90–100 twins) per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovaries to release an egg from each side.