PATHOLOGY

Detailed explanation-1: -Because identical twins develop from a single fertilized egg, they have the same genome. So any differences between twins are due to their environments, not genetics. Recent studies have shown that many environmentally induced differences are reflected in the epigenome.

Detailed explanation-2: -Identical twins have the same set of epigenetic marks on the genome when they are born. But differences in the epigenome emerge as the twins grow older and become greater the longer they live apart, say a team of researchers led by Dr. Manel Esteller of the Spanish National Cancer Center in Madrid.

Detailed explanation-3: -Because identical twins share all of their genes, their measurements of IQ and sleep time will be more similar the bigger role genes play in it (i.e., differences between two identical twins must be caused by the environment because their genes are the same).

Detailed explanation-4: -Advantages of twin studies Researchers can estimate the proportion of variance in a trait attributable to genetic variation versus the proportion that is due to shared environment or unshared environment.

Detailed explanation-5: -Environmental Differences While identical twins form with the same set of genes, human development is not just genetic. The environment also has an impact. 1 So, beginning in the early environment of the womb, external influences can change the appearance of twins. For example, some monozygotic twins share a placenta.