Secret to a long life

[rebbonk]

A grandfather tells his grandson the way to along life is to take a pinch of gunpowder every morning on his oats, he does this and dies aged 103.

He leaves:-

14 children,

25 grand children,

40 great grandchildren,

14 great great grandchildren

and

Spoiler:

a 15 metre crater where the Crematorium stood!