Identical twins do indeed possess the same DeoxyriboNucleic Acid, or DNA, at the cellular, molecular level. However, because each twin is subjected to different environmental factors, they can develop different genomic traits.
Factors Influencing DNA Variations
Other factors that can cause the DNA of identical twins to vary slightly include diet and smoking. There is some scientific debate as to whether these minute underlying differences can support the argument that identical twin DNA is in fact different. The similarities between identical twin DNA are borne out in other ways. For example, Toronto identical twin Robin Barfoot, despite living in a different country for 40 years from his identical twin brother, had bypass surgery within a few days of his sibling and was outfitted with the same type, size and manufacturer of artificial aortic valve.
A Village of Twins
One of the strangest repositories of identical twin comparison talent pools is the Indian village of Mohammadpur Umri. Although it may appear to be a typo, among the community’s 300 or so residents are a staggering 54 different pairs of identical twins. That translated to a pair of identical twins in every fifth home, the highest concentration of any place in the world. One family even has four pairs of twins. It’s likely that this community will prove to be, if properly measured, the most fertile research ground for comparing the subtle differences in twin DNA.
Chances of Having Twins
Separately, several scientists from Singapore and the World Health Organization have begun analyzing what in the DNA of the community as a whole may account for this extraordinary preponderance of identical twins. Based on saliva and blood samples, the researchers are hoping to identify the genetic variant that is responsible. Part of the explanation may have something to do with hyper-ovulation among women, a tendency that can be genetically passed on. Normally, the chances of a woman giving birth to a pair of identical twins is one in 300.
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American Heart Association – Mechanical Control of Tissue Morphogenesis, 2008, Retrieved November 4, 2010 from http://circres.ahajournals.org/cgi/content/full/103/3/234?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=embryos&searchid=1&FIRSTINDEX=0&resourcetype=HWFIG#R11-175331
Wisconsin Radio Network – “UW Health Introduces Palm Scanning”, October 27, 2010, Retrieved November 4, 2010 from http://www.wrn.com/2010/10/uw-health-introduces-palm-scanning/