Identical Twins Are Not Genetically – Latest News, Breaking News, Top News Headlines – CVBJ – Latest News, Breaking News, Top News Headlines

If you have an identical twin and you dislike being called your clone, scientists say you have good reason for it.

New research reveals that identical twins are not genetically identical.

Scientists in Iceland sequenced the DNA of 387 pairs of identical twins – born from a single fertilized egg – as well as their parents, children and spouses. Thus they found “early mutations that separate identical twins,” said Kari Stefansson, a geneticist at the University of Iceland and the company deCODE Genetics and co-author of the study published Thursday in the specialized journal Nature Genetics.

A mutation means an alteration in the DNA sequence, a tiny change that is not good or bad in itself, but which can affect physical traits or susceptibility to certain diseases. They occur when a cell divides and a small error occurs when DNA replicates.

Identical twins have an average of 5.2% of these early genetic differences, according to the study. But 15% of twin sets have more genetic differences, some as many as 100, Stefansson said.

These differences represent a tiny portion of each twin’s genetic code, but it can determine why one of them is taller or why one is more susceptible to certain cancers.

Previously, many researchers believed that the physical differences between identical twins were due to environmental factors, such as nutrition or lifestyle.

Jan Dumanski, a geneticist at the University of Uppsala, Sweden, who was not involved in the research, considered it “a clear and important contribution to medical research.”

“Hence it follows that we must be very careful when using twins as models” to differentiate the influences of nature and nurture, he said.

Previous studies, such as one from 2008 published in the American Journal of Human Genetics, identified some genetic differences between identical twins.

The new study goes beyond the previous ones by including the DNA of parents, children and spouses of identical twins. This allowed the researchers to determine when genetic mutations occurred in two classes of cells: those present in an individual and those inherited by their offspring. They found mutations prior to the embryo dividing in two.

Stefansson said his team found pairs of twins in which the mutation is present in all cells of one but does not appear in the other. However, “sometimes the second twin shows the mutation in some cells, but not all.”

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