Blood Relations

Draw a family tree: + for male, - for female, horizontal line for couples, vertical for parent-child. Never hold it in your head.

Start with this

'Pointing to a man, Rani says, his mother is my mother's only daughter.' Rani's mother's only daughter is Rani herself. So the man is Rani's son. Break the sentence from the end.

Blood relation questions become easy with a family tree and a fixed set of symbols. Always decode from the end of the sentence.

Draw a family tree

Worked example

Pointing to a man, Rani says: 'His mother is my mother's only daughter.' How is the man related to Rani?

1. 'My mother's only daughter' is Rani herself.
   Why: Start from the end of the sentence.
2. So the man's mother is Rani.
3. The man is Rani's son.

Answer: Son

Worked example

A is B's brother. C is A's mother. D is C's father. How is B related to D?

1. A and B are siblings, both children of C.
   Why: Brothers share parents.
2. D is C's father, so D is the grandfather of A and B.
   Why: Two generations up.
3. B is D's grandchild.

Answer: Grandchild

Coded relations

'A + B means A is the son of B, A - B means A is the wife of B ...'. Decode each symbol into a small tree, then join the trees.

Worked example

P # Q means P is the brother of Q; P @ Q means P is the mother of Q. What does X @ Y # Z mean?

1. Y # Z: Y is Z's brother, so Y and Z share parents.
   Why: Decode each symbol.
2. X @ Y: X is Y's mother.
3. So X is Z's mother too.

Answer: X is Z's mother

Shortcut: Pointing / introduction questions

Use it when: 'Pointing at a man, Rita said, "His mother is the only daughter of my mother."'

1. Only daughter of my mother = Rita herself.
2. So Rita is his mother.

Pointing / introduction questions: try it

How is the man related to Rita?

1. Son.

Answer: Son

Your turn medium

Pointing to a photo, Arun says, 'She is the daughter of my grandfather's only son.' Who is she to Arun?

1. Grandfather's only son = Arun's father.
2. His daughter = Arun's sister.

Answer: Sister

Your turn medium

If P + Q means P is the father of Q, P - Q means P is the wife of Q, and P × Q means P is the brother of Q, what does A - B + C mean for A and C?

1. A is B's wife; B is C's father.
2. So A is C's mother.

Answer: A is C's mother

Your turn medium

A is the son of B. C is B's sister. D is C's son. How is D related to A?

1. C is A's aunt.
2. Her son D is A's cousin.

Answer: Cousin

Recap

• draw a tree with fixed symbols
• decode 'pointing' sentences from the end
• turn coded symbols into small trees and join them

Now practise

4 questions with full solutions.

Open practice Back to the lesson