Blood relation questions test your ability to trace family connections through chains of clues and arrive at the relationship between two specific people. The exam is not testing general knowledge about families — it is testing whether you can build a mental model fast and read from it accurately.
Think of it like wiring a circuit board. Each clue is a wire connecting two nodes. Your job is to lay down all the wires first, then trace the path between the two nodes you are asked about. The mistake most people make is trying to trace while still reading clues — which leads to confusion and errors.
Here is the core analogy that will anchor everything: imagine a family tree as a building with floors. Each floor is one generation. People on the same floor are siblings or spouses. People one floor up are parents, one floor down are children. Two floors up is grandparents' level. The moment you receive a clue, you are being told which floor and which side of that floor someone stands on.
There are three question types you will see in RRB NTPC:
Type 1 — Direct chain. A series of statements like "A is the father of B, B is the sister of C…" and you are asked how A relates to C. Solved by drawing the chain.
Type 2 — Coded/symbol-based. Operators like $, #, @ are defined, and you decode an expression like A $ B @ C # D. The chain is the same — just hidden behind symbols.
Type 3 — Counting and extended family. A paragraph describes a family and asks how many members are there, or asks you to verify consistency of given conditions. These require careful counting, not just tracing.
The reason blood relations feel confusing is gender ambiguity. "X is the sibling of Y" — is X male or female? Exam setters exploit this. Your defence is to always note gender explicitly when given, and mark it on your diagram with (M) or (F).
Stop solving blood relation questions in your head. The moment you see a question with four or more people, put pen to paper. A rough diagram takes 20 seconds and saves 60 seconds of mental re-tracing.
Diagram conventions:
= between two people → married couple(M) and (F) labels on every person you can genderStep-by-step process:
When you trace a path, count the generation moves:
| Path | Relationship | |---|---| | One step up | Parent (father/mother) | | One step down | Child (son/daughter) | | Two steps up | Grandparent | | Two steps down | Grandchild | | Three steps up | Great-grandparent | | Same level, different family branch | Cousin | | One step up then down (through a different child) | Uncle/Aunt (up) → Nephew/Niece (down) |
The cousin vs uncle/aunt trap is the most common error. If you go up one generation to a grandparent and down two, you reach a cousin. If you go up one to a parent's sibling and down one, you reach a cousin. These are first cousins — children of siblings.
Look at an expression like: A $ B @ C # D
Decode left to right, one operator at a time:
A $ B → A is father of B. Draw: A → B (A one generation above B)B @ C → B is husband of C. Draw: B = C (same generation, married)C # D → C is mother of D. Draw: C → D (C one generation above D)Now your tree: A → B = C → D
A is two generations above D. A is D's grandfather.
The key rule: never skip the intermediate drawing. Even experienced solvers misread chains like A $ B @ C when they try to do it mentally.
When asked to count the total number of people, the method is:
For the "consistency check" variant — "Each son has 2 brothers and 2 sisters" — this is just verifying your family count rather than adding information. Use it to confirm your diagram is right, not to re-derive it.
Maternal vs Paternal:
In-law chain:
Generational titles:
One point that catches people: "F is the father of E, G is the sister of E" — G is also F's daughter. Do not make G a separate generation. The question is testing whether you assign the correct generation to all new people introduced.
Every clue moves you UP or DOWN one floor (generation) or SIDEWAYS (same generation). As you read each clue, say aloud: "up", "down", or "sideways". After reading all clues, count the net up/down moves to identify the generation gap. Generation gap of 0 = sibling/cousin level; gap of 1 = parent/child or uncle/niece; gap of 2 = grandparent/grandchild or first cousin once removed. Standard method: re-reading clues 2-3 times = 90s. Elevator counting = 25s.
In coded blood relation chains, always decode strictly left to right, one symbol at a time, and write the decoded relationship before moving to the next symbol. Example: A $ B @ C # D — write "A=father of B" before touching the @. This prevents the common error of misassigning the subject and object of a symbol. Standard method (mental): 3-4 re-reads = 60s. Left-to-right lock (on paper): one pass = 20s.
If two people share a grandparent but not a parent, they are first cousins — no need to trace the full path. The moment you see "A is B's mother's brother's son" or any "parent's sibling's child" construction, call them cousins instantly. Tracing step by step: 5 steps = 40s. Pattern recognition = 8s.
As soon as gender is confirmed (via "son", "daughter", "wife", "husband", "brother", "sister"), write M or F next to that name in your diagram. This takes 1 second per person but eliminates the most common trap: misgendering someone halfway through a long chain and arriving at "grandfather" when the answer is "grandmother". Every time you draw a new node, ask: do I know the gender? Mark it immediately or mark it as "?" — never leave it blank and assume.
For counting questions, first count just the named family unit (direct members), then add the extended members separately, then verify against the consistency conditions given in the question. Three-step verification catches double-counting errors. Doing it in one pass: 70% error rate on complex questions. Count-then-confirm: near-zero error rate. Adds only 15 seconds.
In the exam hall, follow this decision tree:
Step 1 — Identify the type. Does the question use symbols/operators? → Coded type. Does it ask "how many people"? → Counting type. Otherwise → Direct chain type.
Step 2 — Start your diagram immediately. Do not read the question twice before drawing. Start drawing after reading the first clue.
Step 3 — Gender-lock as you go. Every new name — mark M, F, or ?.
Step 4 — Trace only after all clues are on paper. Find the two people the question asks about. Trace path: count generation moves up and sideways and down.
Step 5 — Eliminate options by gender first. If the answer must be female (you are tracing to a woman), eliminate all male-relationship options immediately before re-reading your diagram.
Time budget: A straightforward 3-clue chain should take under 45 seconds. A 6-8 clue complex chain with extended family should take under 90 seconds. If you are past 90 seconds, mark your best answer and move on — blood relation questions rarely justify more than 2 minutes.
Why this question: Tests the counting variant — easy to over-count or under-count if you conflate the two family units.
Solving path: Start with the man's immediate family. He has 3 sons and 2 daughters — that is 5 children. Add the man and his wife: 7 people. The clue that "each son has 2 sisters and 2 brothers" confirms there are exactly 2 sisters (daughters) and 2 brothers (among the sons), which matches 3 sons and 2 daughters. No new information, just confirmation. Wife's sister is a separate person (1) with 2 sons (2) and 1 daughter (1) — that is 4 people. Total: 7 + 4 = 11.
Why this question: Multi-generation chain with an "if there are two generations" qualifier that confuses solvers who do not track generations carefully.
Solving path: Build upward. M is N's son, P is M's father — so P and N are the same person (or P = father of M = N). Q is P's sister. R is Q's mother — which makes R also P's mother (one generation above P). S is R's father (one generation above R), T is S's wife. So the chain from M upward is: M → P (father) → R (grandmother) → S/T (great-grandparents). T is M's great-grandmother.
Why this question: Tests whether you correctly identify the cousin relationship through an uncle-of-parent path.
Solving path: X = Y are married. F is Y's brother. Z and W are X and Y's twins. B is Z's son. H is F's son. Since F is Y's brother, F is the uncle of Z and W. B is Z's child; H is F's child. Z and F are one generation apart (Z is F's nibling). But B and H are in the same generation — both are children of people in the Z/F generation. Since their parents (Z and F) are uncle and nephew/niece to each other... wait — simpler: F is Y's brother, Y is Z's parent, so F is Z's uncle. F's child H and Z's child B are first cousins (their parents are uncle-nephew, one generation apart — no, their parents Z and F are sibling-of-parent level). The correct read: Y is parent of Z, F is sibling of Y, making F Z's uncle. H (F's son) and B (Z's son) share Y's generation as grandparent-level reference. They are first cousins.
Why this question: Tests the father-in-law to grandfather conversion — a one-step inference that many miss.
Solving path: A is father of B and C. D is brother of C — but wait, D is brother of C and E is mother of D. So E is mother of both D and C (since D is sibling of C). A is father of B and C, E is mother of D and C — E must be A's wife. F is father of E. So F is A's father-in-law. Father-in-law of a parent = grandparent of the children. F is grandfather of B.
Why this question: Classic symbol-decoding chain — exactly what RRB NTPC loves for quick point pickup.
Solving path: Decode left to right. A $ B → A is father of B. B @ C → B is husband of C (so B and C are married). C # D → C is mother of D. Chain: A is father of B; B is married to C; C is mother of D. So A is the father of D's father (B). A is D's grandfather.
Misreading "brother-in-law" direction. Brother-in-law can mean your spouse's brother OR your sibling's husband. When the question says "P is the brother-in-law of Q", always check whether Q is female (making P her husband's brother) or male (making P his sister's husband). The two cases lead to completely different family structures.
Assuming unnamed spouses don't exist. If the question says "A is the father of B" and later says "C is the mother of B", C is A's wife — an implicit connection. Many solvers draw A and C as separate from each other and then get confused about why the family has two parents with no marriage link.
Confusing "son" with "son-in-law". When a question uses just "son", it means biological/adopted son, not son-in-law. If the question means son-in-law, it will say so. Don't invent in-law relationships where the question uses direct family terms.
Skipping the gender check on the final answer. You trace the path correctly, count generations correctly, but you have not locked the gender of the person you are tracing to. Result: you write "grandfather" when the answer is "grandmother". Always check: is the person at the end of the chain male or female?
Double-counting in extended family questions. The wife's sister is a separate person from the wife. The wife's sister's sons are separate people from the man's sons. When counting, list each family unit separately and add, rather than merging them into one list where duplicates can slip in.
Treating consistency-check clues as new information. When a question says "each son has 2 sisters and 2 brothers" — this is a verification condition, not a new clue that adds people. If you already have 3 sons and 2 daughters, this clue just confirms your count. Using it to "add" people inflates your answer.