The overwhelming impact of methylation pathway mutations is exemplified by the July 9, 2005 article in Science News, which reported that although identical twins have the identical DNA they often have differences in a number of traits including disease susceptibility. This study suggests that as twins go through life the environmental influences to which they are exposed affects which genes are actually turned on or off. Methyl or acetyl groups can attach to the DNA in a similar way that charms attach to a charm bracelet. This modification of the DNA is known as epigenetic regulation. The combination of environmentally determined addition of these “charms” to the bracelet of DNA combined with inherited DNA changes or mutations lead to an individual’s susceptibility to disease. According to the scientist who headed this study, Dr. Manuel Estseller, “My belief is that people are 50 percent genetics and 50 percent environment.” This statement should give us some understanding as to why mutations in the methylation pathway can be so devastating. Mutations in the methylation pathway affect the 50% of the pure genetic susceptibility; this would be analogous to defects in the links of the chain of our charm bracelet. In addition, because methylation is also necessary for the epigenetic modification of the DNA, methylation also affects the environmental 50%. If we take the analogy a step further to really understand the global impact of defects in this pathway we can view genetically inherited mutations in the methylation pathway as causing problems in the links of the bracelet and environmental effects creating a problem with the ability to put charms on the bracelet of DNA. Problems in the methylationpathway therefore can affect 100% of our susceptibility to disease.