How to Solve Blood Relation and Family Generation Puzzles
Solve blood relation and family generation puzzles by drawing a generation tree edge by edge, with worked examples and practice questions.
Expected Interview Answer
Blood relation puzzles are solved by drawing a family tree top-down by generation, converting every stated relation into a parent-child or spouse edge, and reading the final answer off the diagram instead of chaining relation words in your head.
Start with a blank generation grid — grandparents on top, parents in the middle, children at the bottom — and place each named person as a sentence is processed, using "+" for a married couple on the same row and a vertical line for parent-to-child. Gender-neutral terms like “child of,” "sibling of," and “spouse of” should be resolved into concrete male/female nodes only when the puzzle states gender explicitly; otherwise keep the node generic and answer only what is determinable. Composite terms are the usual trap: "paternal uncle" is the father’s brother, "maternal grandmother" is the mother’s mother, and these compress in one sentence what would otherwise be two edges, so expand them into two separate edges on the tree. Once every clue is plotted, the requested relation is read directly by tracing the path between the two nodes rather than re-deriving it from the words.
- A drawn tree eliminates the working-memory limit of chaining relations mentally
- Generation rows make gender and generation-crossing errors visually obvious
- Composite terms decompose into two simple edges, removing ambiguity
AI Mentor Explanation
A cricket commentator building a player’s family cricketing lineage sketches a tree: grandfather played first-class cricket, his two sons include the current captain, and the captain’s child is a rising junior player. Each fact — "X is the father of Y," "Y and Z are siblings" — becomes one edge added to a growing diagram rather than a sentence to re-read later. When someone asks how the junior player is related to the grandfather, the commentator just traces two edges down the tree instead of re-parsing every original sentence, exactly how blood relation puzzles should be solved.
Step-by-Step Explanation
Step 1
Draw a blank generation grid
Rows for each generation (grandparents, parents, children); "+" links spouses, vertical lines link parent to child.
Step 2
Process clues one at a time
Convert each sentence into exactly one or two edges; add the node only when its generation is clear.
Step 3
Expand composite terms
"Paternal uncle," "maternal grandmother" etc. decompose into two edges each — never solve them as one leap.
Step 4
Trace, don’t re-derive
Once the tree is complete, answer by tracing the path between the two named people on the diagram.
What Interviewer Expects
- Immediately sketches a generation tree rather than reasoning purely verbally
- Correctly decomposes composite relation terms into two edges
- Distinguishes blood relations from relations by marriage when the puzzle requires it
- Verifies the final answer by re-tracing the path on the completed diagram
Common Mistakes
- Attempting to hold the entire relation chain in working memory instead of drawing it
- Misreading “brother’s son” as sibling instead of nephew
- Assuming gender for a generic term like “child” or “cousin” without textual support
- Confusing generation direction, e.g. treating a grandparent’s edge as a sibling edge
Best Answer (HR Friendly)
“I always draw the family tree as I read the clues, one edge per sentence, using generation rows so I never lose track of who is above whom. Composite phrases like paternal uncle I break into two simple edges — father, then his brother — rather than trying to solve them in my head. Once the tree is complete, the answer to “how is X related to Y” is just tracing the path between the two nodes.”
Follow-up Questions
- How would you represent an adopted or step relation differently on the tree?
- How do you handle a puzzle where gender is never stated for one person?
- What is the fastest way to verify a blood relation answer once the tree is drawn?
- How would you extend this method to a four-generation puzzle?
MCQ Practice
1. Pointing to a photo, Ravi says, "She is the daughter of my grandfather’s only son." If Ravi has no siblings, how is the girl related to Ravi?
Grandfather’s only son is Ravi’s father, so the father’s daughter (with Ravi having no siblings) is Ravi’s sister.
2. A is B’s father. C is B’s sister. D is C’s husband. How is D related to A?
C is A’s daughter (sibling of B, child of A), and D married C, making D A’s son-in-law.
3. "Q is the son of P’s brother" tells you Q is P’s:
P’s brother’s son is, by definition, P’s nephew — one generation down from P via a sibling edge.
Flash Cards
Best first step on any blood relation puzzle? — Draw a blank generation grid before processing any clue.
How to handle “paternal uncle”? — Decompose into two edges: father, then father’s brother.
Symbol convention for spouses vs parent-child? — "+" links spouses on the same row; a vertical line links parent to child.
How is the final answer found? — Trace the path between the two named nodes on the completed tree — never re-derive from the text.