Altered states

摘要

Marie and Jo―not their real names―are twins, genetically identical and raised in a happy home. Growing up, both enjoyed sport and art, were equally good at school, and appeared similar in almost every respect. But as adults, their lives and personalities diverged: in her early twenties, following episodes of hallucinations and delusions, Marie was diagnosed with schizophrenia. Such examples have long baffled geneticists. Despite sharing the same DNA and often the same environment, 'identical' twins can sometimes show striking differences. Now some researchers are beginning to investigate whether subtle modifications to the genome that don't alter its DNA sequence, known as epigenetic changes, may provide the answer. In doing so, they hope to shed light on the mysterious roots of common diseases―such as schizophrenia and diabetes―that burden society as a whole.