Identical twins more often resist being called a clone of their siblings; however, new research has proved they might not be genetically the same. Scientists from Iceland have analyzed DNA sequences from 372 identical twins and from their parents as well. Identical twins are born out of a single fertilized egg. The co-author of the study and geneticist at the University of Iceland and the company deCode, Kari Stefansson has said that the study has helped him to find out early mutations, which are responsible for separating identical twins. The findings of the study have been released in the journal called Nature Genetics. A mutation can be defined as an alteration in a sequence of DNA, a slight change, which is not inherently good or bad but can affect physical features and vulnerability to certain diseases in children. Such mutations take place when a cell divides and makes a tiny error in replicating DNA.
The study has found that around 5.2 of these initial genetic differences are found in identical twins. However, nearly 15 percent of identical twin pairs have been found with even more genetic differences. Some of them have been found with more than 100 genetic differences, said the experts. The co-author of the study has said that these differences show a tiny bit of the genetic code of each twin but they might explain why one twin is taller and why one twin is at a higher risk of chronic disease such as cancer. Earlier, many scientists have thought that physical differences between identical twins have been linked to environmental factors such as lifestyle and nutrition. A geneticist at Uppsala University in Sweden, Jan Dumanski has said that the findings of the study have made a great contribution to medical research. He has said that the only implication of this study is that scientists will have to be very attentive while using twins as models for testing the impacts of nature and nutrition. Past studies along with a paper, which has been published in 2018 in the American Journal of Human Genetics, have reported that there are some genetic differences between identical twins.
The new study has included the DNA of parents, children, and spouses of identical twins, unlike other past studies. These inclusions have helped experts to identify when these genetic differences take place in two different types of cells, which exist in just one individual and are inherited by the children of that person. They have been able to find mutations, which take place before the developing embryo splits into two, which sets the stage for twins. The team of experts has identified some pairs of identical twins where a mutation exists in all cells of the body of one twin but that mutation is not found in the other twin. However, at times the other twin might have this mutation in some of the cells, but not in all cells. Many experts have lauded the findings of the study and have said that it is a heroic success. They have said that the study has the potential to change people’s thinking about the effects of genetics and the environment.