McCain’s Mother is something like 94 years old, so he has the longevity genes.
But that said, he obviously will need to pick a strong person for VP, who can take over, should something happen to him.
His father and grandfather were not particularly long lived.
As far as his mother's age is concerned, she's female and they have longer lifespans, plus she wasn't a POW for half a decade.
McCain's dad lived 70 years. His father, also an admiral, lived 61 years.
This guy is a walking timebomb, and the sooner that problem is addressed the better!