Teenager A: I found an interesting relation between my age and the age of my father. Multiplying my age by the age of my father I get the same result if we use the correct ages or if both of us reverse the ages' digits prior to the multiplication.
Same happens if I do it with my grandfather's or even with my aged grand-grand father's ages.
B, A's brother: That applies to my age as well.
C, a friend: My age, too. But no grand-grandfather...
All the ages (A,B,C) are distinct.
What are they?

(In reply to re: possible solution by Ady TZIDON)

Ady,

Not incoherent at all! 

To use your very own example, the Brothers Karamazov were also stepbrothers, but they were still called 'brothers'. And I have no idea of the ages of my 4 great-grandfathers; that 'incoherence' is intrinsic to the original problem.

I'd be happy to have a go at the revised version, once ready.

Posted by broll on 2011-11-21 06:04:29