In a family, there are the following human members: Grandfather, grandmother, father, mother, son, daughter.
All family members are inside a single room now.
Question: What is the minimum amount of people inside the room now?
Consider Anna, Bill and Carl.
Imagine a land where it is allowed to marry your own children
Anna is Bill's daughter. Therefore Bill is her father.
Anna marries Bill.
They both get a son Carl.
So Bill is Carl's father and grandfather.
And Anna is Carl's mother
But, Anna is also Carl's (step-)grandmother because she is married to his grandfather
There are at least
Consider a couple Anna and Bill. They have a son Carl, who has a daughter Dora.
- Anna is a grandmother to Dora
- Bill is a grandfather to Dora
- Bill is a father to Carl (and Carl is a father to Dora)
- Anna is a mother to Carl
- Carl is a son to Anna and Bill
- Dora is a daughter to Carl
You can't have less than this. You need at least 3 generations in order for someone to be a grandparent, for a minimum of 3 people. But since we need both a grandmother and a grandfather, the eldest generation must have 2 people, for a total of four.
Two. A man: who is a grandfather, a father and a son; and a woman: who is a grandmother, a mother and a daughter.
If you allow for time-travel, the answer is ONE.
Read All you Zombies. The protagonist of the story is hermaphroditic, and is his/her own father and mother, therefore also his/her own grandfather and grandmother.
So two people satisfy all the qualifications: a grandfather and a grandmother
Four. Here's one way:
Alice has a son named Bob, who has a daughter named Carol. So, Alice is a mother and a grandmother, Bob is a father and a son, and Carol is a daughter and a granddaughter. They are all in the room. Then, Bob's paternal grandfather Dennis enters the room. So we have:
Grandmother: Alice (to Carol)
Grandfather: Dennis (to Bob)
Father: Bob (to Carol)
Son: Bob (to Alice)
Daughter: Carol (to Bob)
Granddaughter: Carol (to Alice)
Grandson: Bob (to Dennis)
Four people, four generations, six roles, no two people filling the same roles, and no person filling the same role twice.
Unless there's a little bit more clarification on the question...
It could simply be two grandparents. Both of them were born a son or daughter, then had their own children who had children. This means each member is a Grandfather, father, and son, or Grandmother, mother, and daughter all at once. If their children are (by some tragedy) all gone, then the "whole family" is in the room... (jeez that made me sad, just now)
Unless we're talking about a
hermaphroditic grandparent, in which case, we could squeeze it down to 1. I feel like this isn't what the question was getting at, though...
Depending on how you interpret some tricky relationships, there could be only 3 people in the room.
Bill is in the room, and is the father to David and grandfather to Emma. Emma is, obviously, the daughter of David. And David is the son of Bill.
Now, what you didn't know was that Bill used to be Anna before gender-transitioning from female to male, and Anna begot Christina through cloning.
Wait, who's Christina? Well, David used to be Christina before his own gender-transition, which is when (s)he gave birth to Emma - again through cloning.
So, Bill is also the mother of David, and is also the grandmother of Emma.
The modern age, folks: giving us new and interesting answers to age old puzzles!
(I realize David doesn't really have to have switched genders, it could just be that Emma's mom is dead, but this way just feels more complete and less morbid - and also, if you go for cloning in the answer, why not go for it twice anyway!)
Okay, writing that out made me think of another possibility:
Warning: potentially squicky. Again, 3 people, with tricky relationships that are subject to interpretation.
Alice gave birth to Derek through cloning, thus becoming the mother to Derek who is her son.
Then, Alice and Derek gave birth to Eva, who is thus their daughter. Derek is now a father. Alice is both mother and grandmother to Eva. Then, Alice chose to transition into Bob, thus becoming also the grandfather of Eva.
(What are you looking at me like that for? I warned ya! :)
Every man is a son to either parent. Thus Grandfather is a son, and by definition a father at the same time. Every woman is a daughter to either parent. Grandmother is a daughter, and by definition, a mother at the same time.
Not knowing too much about genetics, it could possibly be ONE. If said individual was a chimera, who was hermaphroditic. Technically they could be both son and daughter, and grandmother, mother, grandfather, father if one half of the chimera shared the female genes, and genitalia, and the other half shared the male genes and genitalia. I know, its a convoluted answer, but....
If Kourtney Kardashian decides to follow in her father's/mother's footsteps and becomes Kurtis Kardashian, then brings her son Mason and daughter Penelope to visit their grandmother Caitlyn Jenner, then you will have a biological grandfather, socially grandmother, biological mother, socially father, and son and daughter with only four people. If either Mason or Penelope choose to change their sex, you only need three.