Kodinji, a village in Kerala state of India has been recently on the News with reports of steadily increasing Twin birth rates.
We are always fascinated by twins. There is something quite emotional about sharing a common, even if congested, living space and destiny right at the start of life. And it serves as a good reference point for researchers who would like to debate about nurture vs. nature in the bringing up of children. Assuming the children were separated at birth and they grew up in different environments, it’s interesting to evaluate the role nurture makes in shaping nature, character and disposition, since nature provided a common raw material for the twins to start with.
How do twins come into existence? Sometimes a fertilized egg splits, each half developing into a baby that is identical as the other. Non-identical babies are more common, which results when two eggs are released simultaneously and both are fertilised by separate sperms. The non-identical twins (also called dizygotic) may be conceived at the same time, or one following the other in a single menstrual cycle – so non-identical twins can even have different fathers.
Twin babies
What factors decide that a twin is born? Twins are conceived when a woman hyperovulates, and this tendency is hereditary. This can also happen when women are on pills for several years, and then stop them. It takes a while for the cycle to get normal, and in the meanwhile, their bodies could be producing multiple eggs. Taking fertility drugs or undergoing other fertility treatments increases the chance one may have twins.
Also, a woman’s chance of conceiving twins increases with age, and peaks between the ages of 35 and 39. Mothers of twins are four times more likely to have twins again than a woman who has only had a singleton or is pregnant for the first time.
People in certain geographical location have more twins, but this factor actually points to their eating habits. For example, the women from Yoruba tribe in West Africa consume plenty of cassava, a type of yam or sweet potato. This vegetable probably contains a chemical that causes hyperovulation. Women who consume dairy are five times as likely to have twins.
Certain cultural practices like consanguineous (blood-related) marriages can also be a reason as in the case of Cândido Godói in Brazil, known as the Twins Capital of the World.
Environmental pollutants are also suspects in this phenomenon. The toxins may suppress estrogen and stimulate multiple ovum production.
Researchers have been heading towards Kodinji village in Northern Kerala in India for the past few years. This village has obtained the distinction of having one of the highest incidences of twin births. A community of 15,000 residents, comprising mostly of muslims, has 230 sets of twins, with about 45 twins per 1,000 live births, a figure that is five times more than the global average.
What surprises researchers is that the Kodinji women have neither been exposed to chemicals nor had any unique diet or fertility drugs. In fact, women who moved far away have given birth to twins, as also women who moved in. Perhaps the most interesting fact is that this trend is recent, and what started perhaps forty years back has been on a steady rise.
The last stated cause – the presence of some hitherto unidentified pollutant–may be the cause behind all this double trouble in Kodinji. Of course, the people here consider it as a double blessing only.
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