< The forgotten path of polymathy
I don't have any specific list, as it tends to change, but I can give you an idea, from the top of my head.
My 3 main interests are: Computer Science (that is my formation), Music (a life long passion, that I have been dedicating more time recently), and History (also a life long passion that I have read heavily since childhood).
Aside from these I play chess (I practice on and off from childhood too), I love languages (natural and programming) though I'm lacking seriously here :(, philosophy is something I have been reading recently, antropology too, and many many other things that I'd like to explore more seriously, but you get the gist.
And indeed wise words from your grandfather.