Although identical twins may look pretty similar, at the DNA level, they are not. Identical twins tend to differ by 5.2 genetic changes researchers have suggested in an article. Monozygotic twins, also referred to as identical twins, come from a single fertilized egg and are often studied to determine if particular traits, diseases, or even conditions can result from genetics or environmental influences. For many decades people often thought that identical twins were genetically the same because they are so similar; therefore, differences in their health were considered to be the result of their surrounding environment. But new research has suggested otherwise and that these genetic changes could also account for differences between twins. Researchers in Iceland have interpreted the complete genetic makeup of 381 pairs of identical twins. For 38 pairs, they were genetic duplicates of each other, but differences in DNA were shown that most likely arose in early development. For 39 pairs, there were many differences between twins' DNA, with some having more than 100 changes between them. The patterns of mutations seen by researchers within the genetic DNA of twins suggest that the embryos do not split neatly when twins form. Some twins may arise when a single cell or even a small group of cells split off from the embryo. The number of cells a twin originates from determines how genetically different they are from their twin. If there are more uneven splits of the embryo, that tends to lead to increased differences between twins.
To me, this article was fascinating to learn about and to know that at such an early stage in life a little change in genetic mutations can differ a whole sequence of someone's genetic makeup. I have always thought that identical twins were identical in their genetic make, therefore that is why they look so similar. It's amazing to be see what we can learn by genetic research.