For years scientists were convinced that the root cause of diseases such as bipolar disorder and schizophrenia lay somewhere hidden in the human genome. But the particular genetic sequence that would supposedly be linked to these illnesses remained elusive. So researches turned to the developing theory of Epigenetics. Studies from King’s College in London and related in this article have shown that Epigenetic (changes in gene activity caused by the environment) changes might be responsible for bipolar disorder and schizophrenia. Jonathan Mill and colleagues scanned the genome of 22 pairs of identical twins. For each pair of twins, one of the twins was diagnosed with either bipolar disorder or schizophrenia. With the understanding that chemical methyl groups attached to particular sites on a genome are responsible for the “turning of” and “turning on” of genes, Mill and his team “scanned for differences in the attachment of methyl groups at 27,000 sites in the genome.” The researches found variations in the amount of methylation of up to 20 percent in the gene ST6GALNAC1 (which has been connected with schizophrenia) and differences in the amount of methylation of up to 25% in the gene GPR24 (which had previously been linked to bipolar disorder). Interestingly Mill’s team found that “a gene called ZNF659, showed over methylation in people with schizophrenia and under-methylation in those who were bipolar, suggesting that the conditions might result from opposing gene activity. These findings certainly support the theory of Epigenetic’s being a real factor in behavior and mental illness. They also serve to confirm that bipolar disorder and schizophrenia are related disorders. This relates to our unit in the sense that Epigenetics deals with the expression of the DNA and genetic sequence we are learning about. While we read about how the nucleotides are sequenced, Epigenetics could potentially be responsible for how DNA is expressed.