With whole genome sequencing, accurately deciphering disease risk based on an individual's genome may seem at hand. But a study by Johns Hopkins investigators finds that genomes fail to provide informative guidance to most people about their risk for most common diseases, and warns against complacency born of negative genome test results. The team used data recorded on thousands of identical twins entered into registries in Sweden, Denmark, Finland, Norway and the National Academy of Science's National Research World War II Veterans Twins Registry. They collected information on the incidence of 24 diseases among the twin-pair groups and analysis shows that whole genome sequencing could alert most individuals to an increased risk of at least one disease, signaled by a positive test result, but most people would get negative test results for the majority of diseases studied, failing to forewarn them of the diseases they may ultimately develop.