I was visiting DB a couple of days ago. I am convinced he is smoking in secret (hiding it from SIL). In the last three years he has been diagnosed life-threatening cancer but after some tough chemo and surgery (8 months off work) he was declared fit to return to work and is still being monitored (blood tests once a year). They have two children. Should I make it clear that I noticed? He obviously knows he is not supposed to be smoking otherwise he wouldn't be hiding it. I am in my 40s and he is my older brother.