In the past, when people wanted to learn what might be in their future, they had their tea leaves, palms, crystal ball, or tarot cards read. Now we can do one better and skip the hocus pocus by going straight to science with genetic testing. Give a few cells and get back a scientific yes or no of if you have that gene. The latest round of genetic testing publicly discussed is the longevity gene, which joins dozens of others previously announced. If you have the longevity gene, you are predisposed to live to be 100... Well, a 77% chance of that. You could still get hit by a bus tomorrow. Or if you chain smoke, you probably are lessening your odds, as lifestyle factors still have an impact.
But also if you do not have the gene, it does not mean you won't live to be 100. You still could. The same could be said for any other genetic testing. If you have a specific gene, it does not mean that defines what will happen to you any more than what someone with a crystal ball said a generation ago. It simply means you are predisposed to that condition that was found to be determined by that gene. Our bodies have many more genes that could predispose us to the same or other conditions. Genetic testing still has a long way to go.
Once you find you have a specific gene, what do you do then? Just because you know you have a genetic predisposition for something, how do you use the knowledge to help you? Take the BRCA gene, for example. Women with either the BRCA1 or BRCA2 gene have a higher predisposition to get breast and ovarian cancers. It doesn't mean they will get them, it means they are at higher risk of getting them. Many women who test positive for one of the two BRCA genes will choose to undergo prophylactic oopharectomies or mastectomies to remove the risk. They opt to have surgery just in case. This is for their peace of mind.
I'm not sure I want to know my future. I think I prefer taking each day as it comes. My grandmother lived to be 96, so is longevity in my future? Maybe. But I've had cancer twice; does that tilt the scales the other way? Maybe I'll go get my palm read if I really ever want to know.