Doctors are trying to unravel the mystery of an Indian village boasting 250 sets of twins born to just 2,000 families

The phenomenon has seen almost six times as many twins born than the global average in the remote village of Kodinhi, in Kerala.

In 2008 alone 15 pairs of twins were born in the village out of 300 healthy deliveries and this year is expected to top that number.

In the last five years alone up to 60 pairs of twins have been born, with the rate of twins increasing year-on-year.

Local doctor and twin enthusiast Dr Krishnan Sribiju has been studying the medical marvel of Kodinhi for the past two years.

Although 250 sets of twins have been officially registered in the village Dr Sribiju believes the real number to be far higher.

"In my medical opinion there are around 300 to 350 twins within the village boundaries of Kodinhi," he said.

"What is fascinating is the increasing numbers of twins with each passing year, so much so that I feel in the past ten years the number of twins in Kodinhi has doubled."

According to villagers, the twin phenomenon only started occurring three generations ago.

Dr Sribiju said: "To the best of my knowledge this medical marvel began somewhere between 60 to 70 years ago.

"Without access to detailed biochemical analysis equipment I cannot say for certain what the reason for the twinning is, but I feel that it is something to do with what the villagers eat and drink.

"If that is the case then maybe whatever is causing this exceptional level of twinning can be bottled and provide help for infertile couples." Categorising the twin phenomenon as a naturally occurring anomaly, Dr Sribiju has ruled out genetic factors as the cause due to the localised nature of the village.

He also dismisses any suggestion that the unusual level of twins could be caused by an unknown pollutant pointing to the high number of healthy twins born without any deformities.

"There are lots of reasons for twins, but let me explain the underlying uniqueness of Kodinhi," said Dr Sribiju, 40.

"The number of twins per thousand here is around 45 per 1,000 births.

"Indian, and by that I mean Asian, people on the sub-continent have the lowest acknowledged incidences of twinning in the world at around four per thousand.

"In addition, there is no IVF treatment here because of the prohibitive cost. Global rates of twins being born, especially in the western world, have increased because of artificial insemination."