As I got older, I took the dismissal route. I started to point out that those people in those generations had had heart problems. One had suffered rheumatic fever as a child. One had undiagnosed chronic heart failure.
Now when the *ahem* family curse is brought up, I joke that in my family, making it past fifty-three is a golden ticket to a long life--my other deceased relatives lived into their late 80s and 90s.
I'm not superstitious about the whole thing. Not really. But--knock on wood--I keep my fingers crossed.