Genetic testing for susceptibility to various diseases is available. Currently many of these companies do provide reports and estimates of risk. The risk estimations are “best guesses” and not necessarily robustly supported by the rigorous scientific validation as yet. These companies test for a variety of things, from susceptibility to various diseases like diabetes, obesity cardiovascular disease, Alzheimer's and some cancers to athletic ability , ancestry information, male pattern baldness and reactions to certain food , alcohol, drugs and caffeine.
Having a variant of a gene that has an association with a disease does not necessarily mean you will get this disease or even that absence of the variant will mean you wont. Genes are only one part of the story. Our environment and the carcinogens and other adverse influences we expose ourselves to will impact on our genes. Other genes we may have also may exacerbate or ameliorate the effects of these genetic variants. In some people, knowing we have a variant that has an association with a disease, even if its effect is only small, can be a powerful motivating factor to change. In others this information will be ignored.
We do recognise this is very much a new frontier and the evidence may take some time to accrue one way or other as to the value of this new gene testing. In the meantime many people will want to access these tests for various reasons eg: curiosity, filling in gaps of possible disease risks in those who were adopted , understanding own body and health risks better, contributing to scientific research etc.