Blood Relations — RRB NTPC Reasoning
This topic carries roughly 8% of General Intelligence & Reasoning's 30 questions. Every relationship chain resolves cleanly once drawn as a family tree — the skill is converting each stated relationship into the correct tree symbol immediately, not holding several relationships in your head at once.
1. What RRB NTPC actually asks
Expect direct relationship-chain questions ("A is B's father's brother's daughter — what is A to B?"), and puzzles involving coded genders (e.g., "+" means son of) requiring you to trace a full relationship.
2. The family tree method
Draw a simple tree as you read each clue: a horizontal line connects spouses, a vertical line connects parent to child, and siblings are drawn at the same level connected by a horizontal branch. Label each person with their stated name/letter immediately — never try to hold more than one relationship in your head before drawing it.
3. Key relationship vocabulary
| Term | Meaning |
|---|---|
| Sibling | Same parents (brother/sister) |
| Paternal | Related through the father's side |
| Maternal | Related through the mother's side |
| Father's brother | Uncle (paternal) |
| Mother's sister | Aunt (maternal) |
| Father's sister's husband / Mother's brother's wife | Uncle (by marriage) |
| Sibling's child | Nephew/niece |
| Parent's parent | Grandparent |
"Only son/daughter" is a significant clue — it rules out the existence of any siblings for that person, which can eliminate otherwise-plausible relationship paths.
Worked examples
Q1. Pointing to a photograph, Rahul said, "She is the daughter of my grandfather's only son." How is the woman in the photograph related to Rahul?
Pick an option to check your answer.
Show explanation
Solution. Rahul's grandfather's only son — since Rahul's own father is also a son of Rahul's grandfather, and this is stated as the ONLY son, that son must be Rahul's own father.
So the woman is "the daughter of Rahul's father" — which makes her Rahul's sister. Answer: (a).
Q2. A is B's brother. C is A's mother. D is C's father. E is B's son. How is D related to E?
Pick an option to check your answer.
Show explanation
Solution. Building the tree: D is C's father (D is one generation above C). C is A's mother, and A is B's brother, so C is also B's mother (same parents as A). E is B's son, so E is one generation below B.
Chain: D → C (D's child) → B (C's child, sibling of A) → E (B's child). D is C's father, C is B's mother, B is E's father/mother — D is two generations above B, and B is one generation above E, making D three generations above E: D is E's great-grandfather. Answer: (c).
5. Common traps
- Assuming a gender not stated in the problem. Unless the problem specifies "brother," "sister," "son," or "daughter" explicitly, a "sibling" or "child" could be either gender — don't assume.
- Losing track of generation levels in a long relationship chain. Always draw the tree with generations as horizontal levels, so a miscount is visually obvious.
- Missing the significance of "only son/daughter." This word specifically rules out siblings for that person, often the key to resolving the whole chain.
- Confusing paternal and maternal sides when both appear in the same puzzle — label each branch of the tree clearly as it's drawn.
6. Guessing strategy
If a relationship chain is long, count the net number of generation steps up or down first (ignoring exact identities) — this alone often narrows the answer to "grandparent-level" versus "parent-level" versus "sibling-level," even before working out the precise relationship name.
Summary
- Blood Relations is roughly 8% of General Intelligence & Reasoning's 30 CBT 1 questions.
- Always draw a family tree as each clue is read — never track relationships purely mentally.
- Horizontal lines connect spouses/siblings; vertical lines connect parent to child.
- "Only son/daughter" is a significant clue that rules out siblings for that person.
- Never assume a gender not explicitly stated in the problem.
- Counting net generation steps first often narrows the answer before working out the exact relationship name.
