Question: A family photo contained:
one grandfather, one grandmother;
two fathers, two mothers;
six children, four grandchildren;
two brothers, two sisters;
three sons, three daughters;
one father-in-law, one mother-in-law, one daughter-in-law, one son-in-law
30 people you may think, but no, what is the least number of people here?
Answer:
There are total 8 people.
Four children - 2 boys and 2 girls, their mother and father, and one set of grandparents -
EITHER mother's mother and father's father OR mother's father and father's mother.