"You know exactly what you are going to lose step-by-step so that's very frightening," said Shannon.
She watched Alzheimer's ravage her 50-year-old mother's mind and body.
"The Alzheimer's facilities are locked from the inside because a lot of patients wander and just knowing that my mother was locked behind this door, I'm sorry," said Shannon as she choked up on her words.
Shannon could not save her mom. Now she is focused on saving herself.
She runs in marathons, eats right, stays stress-free and plays brain games but wonders if all of her activities will actually change what she is already born with.
Whether it's Alzheimer's or heart disease, doctors say you do have control. New research shows something called the epigenome makes it possible. Your epigenome interacts everyday with the environment. That means everything you come into contact with or put into your body has the power to turn genes on or off.
The American Institute for Cancer Research (AICR) reports that even with a family history, 45 percent of colon cancers, 38 percent of breast cancer, and 69 percent of esophageal cancers would never occur if Americans ate better, weighed less and exercised more.
"If you're sitting in front of your television watching this, get up afterwards and exercise." Dr. Lewis Lipsitz, Institute for Aging Research.
Although Shannon is doing everything right, she still worries.
"To be honest, every time I forget someone's name, or if I change rooms and I forget where I was going, I'm terrified for an instant that I have Alzheimer's," said Shannon.
The FDA already approved the first drug that acts on the epigenome. It treats leukemia by activating tumor-suppressing genes. About 30 other epigenetic drugs are in development around the world.