Hello and welcome to the forum. Sorry about your delay in response and very sorry to hear about your grandfather. He was very young. There is a genetic component. However, it is most often immediate family members with a rate of 5 to 10 percent of those diagnosed with pancreatic cancer having an immediate family member who has had the disease. There are other risk factors as well. If you are a smoker, have diabetes, are obese, have chronic pancreatitis. https://www.webmd.com/cancer/pancreatic-cancer/causes-pancreatic-cancer
Symptoms of pancreatic cancer are found at this link. https://www.webmd.com/cancer/pancreatic-cancer/pancreatic-cancer-symptoms#1 When they speak of light stools they are speaking in terms of jaundice which usually has other symptoms such as yellow skin or eyes. Do you have that as well? If not, I'd not necessarily associate light stools with pancreatic cancer. GERD is likely to cause yellow stools. Could that be a possibility for you?