Is the DNA of identical twins really identical?
The best answer to the question is, “almost identical”. With respect to the DNA, this refers to the differences in genotype between identical twins. The sequence of the DNA is nearly 100% identical although there are likely to be handful of spontaneous mutations that occurred early in development just after the original fertilized egg had split. Other twins genetic modifications can also occur but they are exceedingly rare. Factors such as DNA imprinting that ultimately control the way that genes are expressed can be more influential than the actual sequence of the DNA. Many environmental factors can influence the control of DNA expression which ultimately lead to changes in the the phenotype or physical characteristics of monozygotic twins. back to top What is the relative impact of genes vs. environment in explaining the differences between identical Indeed, the study of twins provides the best controlled studies that can address this question. For nearly all human traits, both genes
