Dad was occasional smoker

My dad passed away very unexpectedly last winter and had a small life insurance policy. The claim forms ask if the insured was a smoker and what years. To my knowledge he smoked cigarettes in his 20s and quit when I was born. I know that probably starting in my teens he would have the occasional cigarette in social situations (like probably once or twice a month) but he never went back to smoking regularly and I know he had decided to quit even the social smoking several years ago but I don’t know exactly when.

I’ve tried finding information about his policy online but from what I can tell it’s the smallest payout insurance this bank offers and as long as you qualify for the insurance, the premiums are the same for everyone and simply increase with age brackets.

It seems he’s had this policy since I was a kid and I don’t know if he smoked at all at the time and I don’t know what questions he was asked when he applied for it. This is stressing me out so much, can I just tell them he quit when I was born and after that I don’t know?