My grandmother, two of her brothers and her dad had colon cancer. my mother and father haven't it yet. how much is the probability that i'll have it?

Watch your mother: your mother is at great risk of developpiong colon cancer. you should start having screening colonoscopy at a young age, like thirty and fourty and fifty, assuming they are all normal and then every five years after fifty the cancer will start as a benign polyp that could easily discovered by colonoscopy and be removed via the scope so you and your mother have an excellent chance avoiding cancer