In a family there are 3 fathers 2 brothers 3 sisters one husband and one wife 2 brother in law two daughters 3 sons 1 grandfather and one niece . what is the minimum possible person in family?

The minimum possible number of people in the family is 6. This can be achieved by having one grandfather (who is also a father), one husband (who is also a father and a brother), one wife (who is also a mother and a sister), and their three children (two sons and one daughter). The two brothers and two sisters can be accounted for among the children, while the niece can be the daughter of one of the brothers.