D is father of A and grandfather of F. So, A is father of F. Thus, D and A are the two fathers. C is the sister of F. So, C is the daughter of A. Since there is only one mother, it is evident that E is the wife of A and hence the mother of C and C and F. So, B is brother of A. There are three brothers. So, F is the brother of C.
A, the father, is male. B, the brother, is male. C, the sister, is female. D, the grandfather, is male. E, the mother, is female. F, the brother, is male. So, there are four males.