Eight persons A, B, C, D, E, F, G and H belong to a family which consists of three generations, including two married couples. B is the mother of C. E is the sister of the only son of C. A is the paternal grandfather of G, who is the daughter of D. D is the daughter-in-law of A. H is the paternal uncle of F, who is the son of C. How is F related to B?

Let's reconstruct the family tree step-by-step:
B is the mother of C.

F is the son of C. Since B is the mother of C, F is the grandson of B.

Let's verify all other conditions:

E is the sister of the only son of C (F). So E and F are children of C.

H is the paternal uncle of F, so H is the brother of F's father (C must be male, and H is C's brother).

A is the paternal grandfather of G, and G is the daughter of D. D is the daughter-in-law of A (married to C).

Therefore, A and B are married (Generation 1).

C and D are married (Generation 2), along with C's brother H.

E, F, and G are children of C and D (Generation 3).

Since F is the son of C, and B is the mother of C, F is the grandson of B.