Thiruvananthapuram: The puzzle behind the abnormally high rate of twin births in the small Kodinhi village in Mala-ppuram remains unresolved, though a resea-rcher of the University of South Florida thinks some residents, once exposed to something that triggered chemical changes to their DNA, passed it down generations.
The phenomenon came to global attention in 2009, prompting Ms Lorena Madrigal of the University of South Florida and team to visit the village, looking for clues to possible genetic or environmental causes, reports the reputed New Scientist.
Kodinhi has 1,000 twins in a population of 11,000 as against the national average of about one twin in a hundred
The team sketched family trees of about 1,800 people back to the 1860s, which helped them rule out a few suggested explanations. Persistent inbreeding — marriages within families — was thought to beget twins. “However, the team found twins were not more likely from such unions... The recent start and steep rise in twin births also points against cousin marriage being the trigger”. “They alwa-ys practised it”, says Ms Madrigal, who presented work at recent American Association of Physical Anthropologists meeting in Cleveland, Ohio.
Previous media reports had suggested a past disease epidemic for the phenomenon. “People with genes that favoured twins could have been more likely to survive the disease for some reason. But the older villagers interviewed recalled no such epidemic”, says the science magazine.
Published research on the village also rules out an unusual diet or source of water as the cause.
Ms Madrigal and team are yet to crack are whether the twins are identical. The catch is even fraternal twins look similar. This should be resolved by analysing their blood samples.
Twins are identical if they develop from one egg, which splits and forms two embryos, or fraternal, meaning that each twin develops from a separate egg and each egg is fertilised by its own sperm cell.
