The study of identical twins is not only important to understand personality traits, but also for medical advancements in the study of illnesses among twins. Identical twins may look and dress alike. They can even trick people into thinking one is the other. But while these identical twins can mimic behavior and mannerisms, they may not always be carbon copies of each other, genetics-wise.
Study: Identical Twins Differ in Genetic Changes
It is not always that identical twins have exactly the same DNA, IGN reported. In a Nature Genetics report, researchers revealed that the average genetic changes for identical twins are at least 5.2 differences. The study debunks the misconception that identical twins are genetically identical.
It was previously believed that differences in the health of identical twins resulted from their environment. But, the study determined that genetics plays a bigger role in the health differences of identical twins.
Kari Stefansson, Decode Genetics founder and co-author of the study reasoned that their findings questions the conclusion that health changes in identical twins are caused only by environmental factors. The genetics of identical twins are not necessarily identical, which explains why not all identical twins develop autism and other illnesses together.
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Genetical Differences Affect Health of Identical Twins
Identical twins are also called monozygotic twins who come from a single fertilized egg that separate to become two babies. Before the study, it was believed that identical twins carried 100% exact DNA. With this belief, environmental factors was the only known cause of differences in their health.
But, the new findings suggest genetic changes in identical twins can play a significant factor in health differences. The study suggests that mutation divergence can also cause childhood illnesses and metabolic disorders.
Few Identical Twins Carry Same DNA
The researchers in Iceland studied the genetic makeup of 381 pairs of identical twins. The study resulted in 38 pairs of identical twins having the exact same genetic makeup. They were genetic duplicates of each other.
Majority of the study participants showed differences in their DNA. Researchers believe the differences in their genetic makeup happened before one embryo split to form two embryos. If not, the differences may have been created shortly after the embryos split.
Identical Twins are More Different than We Thought
Further, the study determined 39 pairs of identical twins that displayed 100 changes in their DNA. Researchers study the likelihood of the embryo not splitting equally. That is, one embryo may receive more nourishment in the womb than the other, Miami Edu reported. The uneven split of the embryo is likely to lead to more differences between identical twins.
With that in mind, one twin may be shorter than the other. Further, when genetic changes happen during the embryonic development, one twin may have a genetic condition, but the other does not. With this new study, medical researchers have more information that can help them better understand medical illnesses between identical twins.
