Twins are fairly rare worldwide—only one in 80 births results in two babies rather than the standard one. In India, it's even lower, closer to one in 250. Strangely enough though, the village of Kodinhi, which only has about 2,000 households total, has one of the highest rates of twinning (that's the official term) in the world.
The village is very similar to every other hamlet in its region, except that getting acquainted with the local doubles could prove more confusing than usual. Kodinhi attracted the world's attention in 2008, when it was discovered that there were nearly 250 pairs of twins born in the past several decades. That year alone, 15 pairs of twins were recorded being born, though local doctor Krishnan Sribiju believes that there are even more in the region.
The phenomenon is somewhat of a mystery. It is apparently linked to the people of Kodinhi, not the place itself, as women who leave the village to start families are equally as likely to give birth to twins. Some scientists have suggested it has to do with pollutants in the village's water, but Dr. Sribiju refutes this claim, as the rate of birth defects in Kodinhi is no higher than anywhere else in India. Genetic researchers from India, Germany, and the UK are studying the DNA of twins the village to try to understand the mysteriously high twinning rate.