I’m convinced that is all in how you pick your grandparents.
I inherited terrible genes. No males in my family made it past 72. Father, brother, all uncles, died before reaching 72. Main reason I am healthy at 86 is relentless exercise for 30 minutes every day, and I mean 365 days of the year. I began that at age 60. I do Zumba dance class at YMCA every week with much younger people. There is no one close to 86 there.