Blood Relations
Draw a family tree: + for male, - for female, horizontal line for couples, vertical for parent-child. Never hold it in your head.
Why this topic matters
'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
Square for male, circle for female, a double line for marriage, a vertical line down to children. Put each generation on its own level.
Mother's or father's brother = uncle, sister = aunt. Son's wife = daughter-in-law. Brother's son = nephew.
- 'My mother's only daughter' is Rani herself.Start from the end of the sentence.
- So the man's mother is Rani.
- The man is Rani's son.
- A and B are siblings, both children of C.Brothers share parents.
- D is C's father, so D is the grandfather of A and B.Two generations up.
- B is D's 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.
- Y # Z: Y is Z's brother, so Y and Z share parents.Decode each symbol.
- X @ Y: X is Y's mother.
- So X is Z's mother too.
Formula summary
Shortcuts and tricks
Pointing / introduction questions
Use it when: 'Pointing at a man, Rita said, "His mother is the only daughter of my mother."'
- Only daughter of my mother = Rita herself.
- So Rita is his mother.
- Son.
Before you move on, you should be able to...
- draw a tree with fixed symbols
- decode 'pointing' sentences from the end
- turn coded symbols into small trees and join them
Practice questions (4)
Try each one before opening the solution. Or practise them one by one so your score is saved.
easy A is B's brother. C is A's mother. D is C's father. How is D related to B?
- D is C's father; C is B's mother.
Answer: Grandfather
medium Pointing to a photo, Arun says, 'She is the daughter of my grandfather's only son.' Who is she to Arun?
- Grandfather's only son = Arun's father.
- His daughter = Arun's sister.
Answer: Sister
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?
- A is B's wife; B is C's father.
- So A is C's mother.
Answer: A is C's mother
medium A is the son of B. C is B's sister. D is C's son. How is D related to A?
- C is A's aunt.
- Her son D is A's cousin.
Answer: Cousin
Class plan (2 hours, for trainers)
A tested order for teaching this topic in one 2-hour session. Present mode follows the same order.
| 10 min | Warm-up. |
| 25 min | Symbols and trees. |
| 25 min | Pointing-to-a-photo questions from the end. |
| 20 min | Coded relations. |
| 35 min | Practice set. |
| 5 min | Recap. |