Identical twins are often remarkably similar, yet they have distinct differences. This might seem unexpected since they share all of the same genes, but scientists have come up with an explanation.Small differences in which genes are turned on or off, and to what degree, account for the subtle differences in physical appearance or other characteristics, according to a report in the Proceedings of the National Academy of Sciences.For instance, one twin may be more susceptible to a given disease or have certain features not found in the other twin. One possibility underlying these phenomena is that modifications that affect the expression of genes differ between the twins.
