A study shows that while identical twins look alike, they are not clones. Scientists analyzed DNA from 387 pairs of identical twins. They looked for mutations in the early stages of development. A mutation is a change in the sequence of the DNA. This can occur when a cell splits. A change can cause slight differences in the DNA when it splits. A tiny change can create differences in height, intelligence, eye colour and in how easy it is to catch a disease.
The study shows that in about 15 per cent of identical twins, one twin had many mutations that the other did not have. This difference helps explain the "nature versus nurture" debate - whether socializing and upbringing affects human behaviour. The research shows that a tiny difference, and not environmental factors, could be the reason for behavioural characteristics or medical conditions.