Smoking isn't the only thing that causes lung cancer. Exposure to asbestos, for example, causes it as well. What you'd need to know is why she got lung cancer, if that's known, but here's the thing about "genetic" disease; even if there is a genetic disposition to disease in a family, it doesn't mean any particular person in the family will get it, it just means the risk is higher than it would have been otherwise. It is a sign to take good care of yourself. But again, if you know where she got treated or if your father is still around and knows see if you can learn if there was a known cause for her cancer because again, there are other pollutants that can cause lung cancer.
Hello and welcome to the forum. Lung cancer can also be a hereditary disease. Here is some information for you: https://pubmed.ncbi.nlm.nih.gov/24736066/ (copy and paste the link). This article may also be of interest to you regarding genetics of cancer and things to consider. https://www.cancer.gov/about-cancer/causes-prevention/genetics/risk-assessment-pdq I would recommend talking to your doctor about this at your next physical. Please let us know if you have any questions and we are certainly sorry for the loss of your mother!