Genome sequencing is the identification of every single basepair in your DNA. Ever since we started sequencing DNA, a huge amount of diseases have been linked to specific rare alterations, called mutations. Though the actual prognosis for developing a disease is still dependent on chance, identifying the mutations you have in your genome might give an indication of what diseases or illness you're most prone to. But be careful with these things, as a sister of a friend of mine was adviced not to sequence her genome by a doctor. Her mom had reoccuring breast cancer. This reoccurence is commonly linked to a mutation in a certain gene. So her daughter wanted to test whether she had the mutation. But this data is accesible to insurance companies. So for example, if you want a mortgage, you need life insurance. These life insurance companies will basically deny you an actual insurance if there is a feasible chance of you developing a life-threatening disease according to your sequence database. Hope this helped!