Every cell comes with a central control panel, a nucleus that contains your genes and chromosomes—the ultimate instruction manual for your body. The genes you inherited from your mother and your father are largely responsible for how your body—and even your mind—behaves.

If 90-year-old women are arriving at your family get-togethers, you've probably got a good shot at the same route. If, on the other hand, most of your relatives died before 70 from heart attacks and strokes, you may share their risk for heart and blood vessel disease. But even with long-life genes, you have to do your part to ensure healthy aging.

Other illnesses strongly affected by your genetic makeup include breast, ovarian, and colon cancer, and osteoporosis. How you experience emotional stress, anger, or depression may also be influenced by your genetic makeup.