Was my dad’s cancer genetic?

My dad died in 2015 after having lung cancer for a year, he was 46. Never smoked or anything that would harm his lungs. But, he had 4 uncles and all of them died from lung cancer as well and his mom aka my grandma is the only one left out of them. I know there are no exact answers, but it just seems like it was genetic to me. If it was, would I or my brother be prone to having lung cancer? Or my kids in the future?