A study shows that while identical twins can look alike, they are not clones of each other. Scientists analyzed the DNA from 387 pairs of identical twins. These are people born from a single fertilized egg. The scientists looked for mutations in the early stages of development. A mutation is a tiny change in the sequence of the DNA. This can occur when a cell divides. This change causes a slight difference in the DNA when it duplicates. A tiny change can create differences in height, intelligence, eye colour and even in how easily someone can catch a disease.
The study shows that in about 15 per cent of identical twins, one twin carried a "substantial" number of mutations that the other did not have. This difference is important as it sheds light on the "nature versus nurture" debate. This is whether human behaviour is caused by socializing and upbringing, or by a person's genes. The research shows that this tiny difference, and not environmental factors, could be the reason for different behavioural characteristics or medical conditions. A professor said a genetic mutation may be the source of a disease or trait.