Is longevity inherited?

This is a subject which has always fascinated me. As a child, I used to be obsessed by numbers, particularly people's ages (I have seen the same curiosity displayed by a couple of my grandchildren). I use to think that older people died first. My maternal grandfather died a few months before the first prime minister of the country (who was killed), so I assumed that my grandfather was younger than the prime minister. 

Some of my relatives have died at much younger ages than others. My mother's only half brother (a very rich man) couldn't have been more than fifty when he conked off due to a heart attack, just five years after his father (my maternal grandfather) died, perhaps at the age of 75. In those days there was no way of being certain of one's age. I have my original birth certificate (in Gujrati) issued by the municipal committee of the small town (Savar Kundla) where I was born. Among my siblings, only the birth dates of two sisters is verifiable. So we'll never be able to know the exact dates on which my other three siblings were born (although I do know the approximate dates of the two who were the last to be born, because I was nine and eleven years old at the time).

I have observed that Parsis live much longer than other Pakistanis. I have a Parsi friend who must be around ninety years of age. He drinks and eats food rich in cholesterol, yet he's much healthier than most men I know. But I have also observed that South Indians die much earlier (just last month, a politician there kicked the bucket at the age of 58). I wonder if South Indian Parsis live as long as the ones here. 

My own father was 73 when he popped off. Of course, he may have been older, but being a lawyer he must've had a fairly good idea of his age. His own eldest brother died at 68, two other brothers were around 80 when they died. I'll be 75 in four months, so I don't have too long to live. But then, having lived much longer than the average Pakistani, I should be grateful to be still up and around. Let's hope I'm still around at the age of 80.

I have cousins who are older than me (one is 80), and two who died much earlier (one at the age of 69, and another, his half-brother, at 60). So, despite us having the same paternal grandfather, it cannot be said that longevity is inherited.